View source for Cooper's hawk

{{Short description|Species of bird}}
{{For|the chain|Cooper's Hawk Winery & Restaurants}}
{{Very long|date=February 2023|words=23,000}}
{{Use mdy dates|date=August 2021}}
{{Speciesbox
| status = LC
| status_system = IUCN3.1
| status_ref =<ref name="iucn status 13 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Accipiter cooperii'' |volume=2016 |article-number=e.T22695656A93521264 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22695656A93521264.en |access-date=13 November 2021}}</ref>
| image = Accipiter cooperii m Sam Smith Toronto3.jpg
| genus = Astur
| species = cooperii
| authority = ([[Charles Lucien Bonaparte|Bonaparte]], 1828)
| range_map = Accipiter cooperii map.svg
| range_map_caption = {{leftlegend|#FF7F2A|Breeding}}{{leftlegend|#7137C8|Year-round}}{{leftlegend|#5F8DD3|Non-breeding}}
}}

'''Cooper's hawk''' ('''''Astur cooperii''''') is a medium-sized [[hawk]] native to the North American continent and found from southern Canada to Mexico.<ref name= Ferguson-Lees>{{ cite book | last1=Ferguson-Lees | first1=J. | last2=Christie | first2=D.A. | date=2001 | title=Raptors of the World | location=Boston | publisher=Houghton Mifflin | isbn=0-618-12762-3 | pages=588–590 | url=https://archive.org/details/raptorsofworld0000ferg/page/588/mode/1up | url-access=registration }}</ref> This species was formerly placed in the genus ''[[Accipiter]]''. As in many [[birds of prey]], the male is smaller than the female.<ref name= Snyder>Snyder, N. F., & Wiley, J. W. (1976). ''Sexual size dimorphism in hawks and owls of North America (No. 20)''. American Ornithologists' Union.</ref> The birds found east of the [[Mississippi River]] tend to be larger on average than the birds found to the west.<ref name= Pearlstine>Pearlstine, E. V., & Thompson, D. B. (2004). ''Geographic variation in morphology of four species of migratory raptors''. Journal of Raptor Research, 38(4), 334–342.</ref> It is easily confused with the smaller but similar [[sharp-shinned hawk]] (''Accipiter striatus'').

The species was named in 1828 by [[Charles Lucien Bonaparte]] in honor of his friend and fellow ornithologist, [[William Cooper (conchologist)|William Cooper]].<ref name= Palmer>Palmer, R. S., ed. (1988). ''Handbook of North American birds. Volume 5 Diurnal Raptors (part 2)''.</ref> Other common names for Cooper's hawk include: '''big blue darter''', '''chicken hawk''', '''flying cross''', '''hen hawk''', '''quail hawk''', '''striker''', and '''swift hawk'''.<ref name=Bent>{{ Cite journal | last=Bent | first=Arthur Cleveland | author-link=Arthur Cleveland Bent | date=1937 | title=Life Histories of North American Birds of Prey. Part 1: Order Falconiformes | journal=Bulletin of the United States National Museum | series=Bulletin of the United States National Museum. 167 | issue=167 | pages=112–125 | doi=10.5479/si.03629236.167.i | hdl=10088/10017 | url=https://repository.si.edu/handle/10088/10017 | url-access=subscription }}</ref> Many of the names applied to Cooper's hawks refer to their ability to hunt large and evasive prey using extremely well-developed agility. This species primarily hunts small-to-medium-sized birds, but will also commonly take small [[mammal]]s and sometimes reptiles.<ref name=BOW>{{cite journal | last1=Rosenfield | first1=R.N. | last2=Madden | first2=K.K | last3=Bielefeldt | first3=J. | last4=Curtis | first4=O.E. | date=2024 | title=Cooper's Hawk (''Astur cooperii''), version 1.1 | editor-last=Rodewald | editor-first=P.G. | journal=Birds of the World | location=Ithaca, NY, USA | publisher=Cornell Lab of Ornithology | doi=10.2173/bow.coohaw.01.1   }}</ref><ref name= Toland>{{cite journal |last1=Toland |first1=Brian |date=1985 |title=Food Habits and Hunting Success of Cooper's Hawks in Missouri |journal=Journal of Field Ornithology |volume=56 |issue=4 |pages=419–422 |url=https://sora.unm.edu/sites/default/files/journals/jfo/v056n04/p0419-p0422.pdf |access-date=June 13, 2020}}</ref>

Like most related hawks, Cooper's hawks prefer to nest in tall trees with extensive [[canopy (biology)|canopy]] cover and can commonly produce up to two to four [[Fledge|fledglings]] depending on conditions.<ref name= Ferguson-Lees/><ref name= Palmer/> Breeding attempts may be compromised by poor weather, predators and [[Human impact on the environment|anthropogenic causes]], in particular the use of industrial [[pesticide]]s and other [[Organochloride|chemical pollution]] in the 20th century.<ref name= BOW/><ref name= Snyder2>Snyder, N. F. R. (1974). ''Can the Cooper's Hawk survive?'' National Geographic Magazine, 145:432–442.</ref> Despite declines due to manmade causes, the bird remains a stable species.<ref name="iucn status 13 November 2021" />

==Taxonomy==
[[File:Accipiter cooperii DM.ogv|thumb|Video: ''Astur cooperii'']]
Cooper's hawk was [[species description|formally described]] by the French naturalist [[Charles Lucien Bonaparte]] in 1828 from a specimen collected near [[Bordentown, New Jersey|Bordentown]], New Jersey. He coined the [[binomial name]] ''Falco cooperii''.<ref>{{ cite book | last=Bonaparte | first=Charles Lucien | author-link=Charles Lucien Bonaparte | year=1828 | title=American Ornithology; or, The Natural History of Birds Inhabiting the United States, Not Given By Wilson | location=Philadelphia | publisher=Carey, Lea & Carey | volume=2 | pages=1–11, Plate 10 fig 1 | url=https://www.biodiversitylibrary.org/page/58173868 }}</ref> The specific epithet and the common name were chosen to honour the naturalist [[William Cooper (conchologist)|William Cooper]], one of the founders of the New York Lyceum of Natural History (later the [[New York Academy of Sciences]]) in New York City.<ref>{{ cite web | last=Jobling | first=James A. | title=cooperii | work=The Key to Scientific Names | url=https://birdsoftheworld.org/bow/key-to-scientific-names/search?q=cooperii | publisher=Cornell Lab of Ornithology | access-date=24 May 2025 }}</ref> Other common names include the big blue darter and the [[Chickenhawk (bird)|chicken hawk]].<ref name=hbw>{{ cite book | last=Thiollay | first=J.M. | year=1994 | chapter=Family Accipitridae (Hawks and Eagles) | editor1-last=del Hoyo | editor1-first=J. | editor2-last=Elliott | editor2-first=A. | editor3-last=Sargatal | editor3-first=J. | title=Handbook of the Birds of the World | volume=2: New World Vultures to Guineafowl | location=Barcelona, Spain | publisher=Lynx Edicions | isbn=978-84-87334-15-3 | pages=52–205 [161] | chapter-url=https://archive.org/details/handbookofbirdso0002unse/page/161/mode/1up | chapter-url-access=registration }}</ref> Cooper's hawk was formerly placed in the genus ''[[Accipiter]]''. In 2024 a comprehensive [[molecular phylogenetic]] study of the Accipitridae confirmed earlier work that had shown that the genus was [[polyphyletic]].<ref name=catanach>{{Cite journal | last1=Catanach | first1=T.A. | last2=Halley | first2=M.R. | last3=Pirro | first3=S. | date=2024 | title=Enigmas no longer: using ultraconserved elements to place several unusual hawk taxa and address the non-monophyly of the genus ''Accipiter'' (Accipitriformes: Accipitridae) | journal=Biological Journal of the Linnean Society | volume=144 | issue=2 | article-number=blae028 | doi=10.1093/biolinnean/blae028}}</ref><ref>{{Cite book | last1=Mindell | first1=D. | last2=Fuchs | first2=J. | last3=Johnson | first3=J. | date=2018 | chapter=Phylogeny, taxonomy, and geographic diversity of diurnal raptors: Falconiformes, Accipitriformes, and Cathartiformes | editor1-last=Sarasola | editor1-first=J.H. | editor2-last=Grange | editor2-first=J.M. | editor3-last=Negro | editor3-first=J.J. | title=Birds of Prey: Biology and conservation in the XXI century | location=Cham, Switzerland | publisher=Springer | isbn=978-3-319-73744-7 | pages=3–32 | url=https://www.researchgate.net/publication/326086278 }}</ref> To resolve the non-[[monophyletic|monophyly]], ''Accipiter'' was divided into six separate genera. The genus ''[[Astur (bird)|Astur]]'' had been introduced in 1828 by the French naturalist [[Charles Lucien Bonaparte]] with the [[Eurasian goshawk]]  (''Astur gentilis'') later designated as the [[type species]]. The genus was resurrected to accommodate Cooper's hawk together with 8 other species that had previously been placed in ''Accipiter''.<ref name=ioc>{{cite web| editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | editor3-last=Rasmussen | editor3-first=Pamela | editor3-link=Pamela C. Rasmussen | date=February 2025 | title=Hoatzin, New World vultures, Secretarybird, raptors | work=IOC World Bird List Version 15.1 | url=https://www.worldbirdnames.org/bow/raptors/| publisher=International Ornithologists' Union | access-date=24 May 2025 }}</ref>

It appears that Cooper's hawk was the earliest ''Astur'' known to colonize North America with a well-defined fossil record dating back perhaps 0.5-1&nbsp;million years. Fossil evidence shows then that the goshawk came second. Despite the considerably wider range of the sharp-shinned hawk, still considered a member of the ''[[Accipiter]]'' genus unlike the prior species, the ancestors of the sharp-shinned hawk came over the [[Bering Land Bridge]] last.<ref name="Palmer" /><ref name="Kenward">{{cite book |last1=Kenward |first1=Robert |url=https://books.google.com/books?id=_tGnSRa0S6sC&pg=PA274 |title=The Goshawk |publisher=T & A D Poyser |year=2006 |isbn=978-0-7136-6565-9 |location=London, UK |page=274}}</ref><ref>Brodkorb, P. (1964). ''Catalogue of fossil birds: Part 2 (Anseriformes through Galliformes)''.</ref><ref>Emslie, S. D., Speth, J. D., & Wiseman, R. N. (1992). ''Two prehistoric puebloan avifaunas from the Pecos Valley, southeastern New Mexico''. Journal of Ethnobiology, 12(1), 83–115.</ref> Genetic testing has indicated that Cooper's hawk is quite closely related to the American goshawk, unlike the similar superficial characteristics of Cooper's to the sharp-shinned hawk, a close relative of the [[Eurasian sparrowhawk]], which were likely obtained through [[convergent evolution]].<ref name="Kenward" /><ref name="Newton">Newton, I. (2010). ''The sparrowhawk''. A&C Black.</ref> A natural hybrid of a Cooper's hawk and an American goshawk with intermediate physical characteristics was verified via genetic testing of a migrant juvenile in [[Cape May]] and was thought to indicate a northward expansion of Cooper's range into historic goshawk haunts.<ref>Haughey, C. L., Nelson, A., Napier, P., Rosenfield, R. N., Sonsthagen, S. A., & Talbot, S. L. (2019). ''Genetic confirmation of a natural hybrid between a Northern Goshawk (Accipiter gentilis) and a Cooper's Hawk (A. cooperii)''. The Wilson Journal of Ornithology.</ref>

No [[subspecies]] are recognized of Cooper's hawk.<ref name=ioc/> A previously described subspecies, ''A. c. mexicanus'', was discounted due to being weakly differentiated.<ref name= Palmer/><ref name= BOW/><ref>Hellmayr, C. E., & Conover, B. (1949). ''Catalogue of birds of the Americas and the adjacent islands. Vol. 13, Part I, No. 4: Cathartidae-Acciptridae-Pandionidae-Falconidae''. Chicago: Zool. Series, Field Mus. Nat. Hist.)</ref> However, evidence based on genetic markers shows that westerly birds such those in British Columbia populations are genetically differentiated from those in the [[Upper Midwest]], indicating that Cooper's hawk were restricted to at least two [[Pleistocene]] [[Glacier|glacial refugia]] with the [[Rocky mountains]] acting as a natural barrier to gene flow between hawks on either side while breeding.<ref>Sonsthagen, S. A., Rosenfield, R. N., Bielefeldt, J., Murphy, R. K., Stewart, A. C., Stout, W. E., & Talbot, S. L. (2012). ''Genetic and morphological divergence among Cooper's Hawk (Accipiter cooperii) populations breeding in north-central and western North America''. The Auk, 129(3), 427–437.</ref> 

Several of the other similar largish ''Astur'' species in the Americas appear to be closely related, possibly within a [[species complex]], to Cooper's hawk, namely the [[bicolored hawk]] (''Astur bicolor''), widely distributed from southern Mexico to  [[Central America|Central]] and northern South America, and the [[Chilean hawk]] (''Astur chilensis'').<ref name= BOW/><ref name="Lerner">Lerner, H. R., & Mindell, D. P. (2005). ''Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA''. Molecular phylogenetics and evolution, 37(2), 327–346.</ref><ref name= Breman>Breman, F. C., Jordaens, K., Sonet, G., Nagy, Z. T., Van Houdt, J., & Louette, M. (2013). ''DNA barcoding and evolutionary relationships in Accipiter Brisson, 1760 (Aves, Falconiformes: Accipitridae) with a focus on African and Eurasian representatives''. Journal of Ornithology, 154(1), 265–287.</ref><ref>Stresemann, E., & Amadon, D. (1979). ''Order Falconiformes''. In ''Check-list of the Birds of the World'' (E. Mayr and G. W. Cottrell, Editors. Museum of Comparative Zoology, Cambridge, MA, USA. pp. 271–425.</ref> While there is some degree of obvious differentiation from these species in appearance, distribution and behavior,<ref name= Ferguson-Lees/>  In particular, Cooper's hawk is now often considered [[sister group|sister]] to [[Gundlach's hawk]] (''Astur gundlachi'') that is endemic to Cuba and together these two species are sister to the [[bicolored hawk]].<ref name=catanach/><ref name=ioc/>
more nebulous is the relationship of Cooper's hawk to the very similar [[Gundlach's hawk]] of [[Cuba]]. In general the relationship of Cooper's and Gundlach's hawk is muddled and genetic testing indicated that it is possible (but not certain) that Gundlach's may even be insufficiently distinct to qualify as a separate species.<ref name= Rodriguez-Santana/><ref name= Breman/><ref name= Reynard>Reynard, G. B., Short, L. L., Garrido, O. H., & Alayón, G. G. (1987). ''Nesting, Voice, Status, and Relationships of the Endemic Cuban Gundlach's Hawk (Accipiter gundlachi)''. The Wilson Bulletin, 73–77.</ref> It is almost certain that Cooper's hawk would at least qualify as the [[paraspecies]] for the Gundlach's and data has indicated fairly recent colonization and hybridization between the two hawks.<ref name= Rodriguez-Santana/><ref name= Breman/><ref name= Reynard/>

== Description ==
[[File:Accipiter-cooperii-01.jpg|thumb|upright=0.75|Adults may be either brown-grey or blue-grey above, with a distinctive, sizable head]]

Cooper's hawk is a medium-sized hawk as well as roughly average to small-sized for an ''Astur'' species. Compared to related species, they tend to have moderate-length wings, a long, often graduated or even wedge-shaped tail and long though moderately thick legs and toes.<ref name= Ferguson-Lees/> Their eyes tend to be set well forward in the sides of the relatively large and squarish-looking head (though the head can look somewhat rounded if the feathers on the nape are held flush) and a relatively short but robust bill.<ref name= Ferguson-Lees/> They have hooked [[beak|bills]] that are well-adapted for tearing the flesh of prey, as is typical of raptorial birds.<ref name="umich2000"/> 

Generally, Cooper's hawks can be considered secretive, often perching within the [[Canopy (biology)|canopy]], but can use more open perches, especially in the western part of the range or in winter when they may use leafless or isolated trees, [[utility pole]]s or [[Tree stump|exposed stumps]].<ref name="Ferguson-Lees" /> On perched hawks, the wing-tips tend to appear to cover less than one third of the tail, sometimes seeming to barely cover the covert feathers.<ref name="Ferguson-Lees" />

As adults, they may be a solid [[blue-gray]] or brown-gray color above.<ref name="Palmer" /> Adults usually have a well-defined crown of blackish-brown feathers above a paler nape and hindneck offset against their streaked rufous cheeks.<ref name="Ferguson-Lees" /> Their tail is blue-gray on top and pale underneath, barred with three black bands in a rather even pattern and ending in a rather conspicuous white tip.<ref name="Ferguson-Lees" /><ref name="allaboutbirds1">{{cite web| url= http://www.allaboutbirds.org/guide/Coopers_Hawk/lifehistory |title= ''Cooper's Hawk''| publisher= Lab. of Ornithology, [[Cornell University]]| website= allaboutbirds.org}}</ref> The adult's underside shows a bit of whitish base color overlaid heavily with coarse, irregular [[rufous]] to [[cinnamon]] bands, though these narrow into marginal shaft streaks around the throat. Against the rich color on the rest of the underside, the pure white {{birdgloss|crissum}} on adults is conspicuous.<ref name="Ferguson-Lees" /> Adult females may average slightly more brownish or grayish above, while some adult males can range rarely into almost a powder blue color.<ref name="Palmer" /> 

Although little regional variation is known in the plumage, adult coloring in the [[Pacific Northwest]] averages slightly darker overall.<ref name=BOW /> Aberrant pale plumage was recorded in at least four total birds of both sexes, all of which were almost completely white and lacked any underside streaking. These birds had faded back color and lacking strong barring on the tail. An aberrant dark female was also recorded. As a juvenile, she had a blackish-brown (rather than mid-brown) back and dark inky feathers below with grayish ground color barely showing. Later she produced an aberrant male with similar characteristics that successfully fledged. The latter two were possible cases of [[melanism]] and such dark variations are virtually unprecedented in any ''Astur'' or ''Accipiter'' species.<ref name="Morrow">Morrow, J., & Morrow, L. (2015). ''Aberrant plumages in Cooper's Hawks''. Journal of Raptor Research, 49(4), 501–505.</ref>

Juveniles of the species are generally dark brown above, though the feathers are not infrequently edged with rufous to cinnamon and have a variable whitish mottling about the back, wing coverts and, mainly, the scapulars. Juvenile Cooper's tend to have streaking or washing of tawny on the cheeks, ending in a light nuchal strip, giving them a hooded appearance unlike the capped appearance of adults (some juveniles, unlike adults, may manifest a slim [[supercilium]] as well). The crown is brown on juveniles rather than blackish as in adults. The tail is similar to that of the adult but more brownish and sometimes shows an additional fourth band. The juvenile has more pale white to cream base color showing than older birds, with variable dusky throat striping and mid-brown streaks, which appear as sharply defined from about the lower throat to the lower breast. The juvenile may have brown to black spots or bars on the thighs with thin black streaks mostly ending at the belly and conspicuous white crissum and undertail coverts.<ref name="Ferguson-Lees" /> Juveniles can tend to appear more "disheveled" and less compact than adults in feather composition.<ref name="Brown">Brown, Leslie and Amadon, Dean (1986) ''Eagles, Hawks and Falcons of the World''. The Wellfleet Press. {{ISBN|978-1555214722}}.</ref> 

In flight, though usually considered medium-sized, Cooper's hawks can appear fairly small.<ref name="Palmer" /> This effect is emphasized by the short wings relative to the elongated tail (unlike unrelated hawks, the wingspan is usually less than twice as broad as the total length).<ref name="Ferguson-Lees" /> The species tends to have rounded wings, a long rounded tail and long legs, much like other ''Astur'' and ''Accipiter'' species.<ref name="Palmer" /> Cooper's hawks have a strong flight with stiff beats and short glides, tending to do so on quite level wings with wrist thrust forward yet the head consistently projects.<ref name="Ferguson-Lees" /> The 5 outer functional primaries are notched on their inner webs, the outermost is the longest, the next outermost nearly as long.<ref name="Palmer" /> When soaring, these hawks do so on flattish or, more commonly, slightly raised wings, with fairly straight leading edges. Against the barred underbody on adults, the wings are more or less flecked in similar color, with pale greyish flight feathers and a broadly white-tipped tail correspondingly barred with dark gray. Meanwhile, the upperside of adults is essentially all blue-grey. Juvenile are mostly dark above though manifest a hooded effect on the head and a rufous-buff edges and especially whitish mottling, the latter can be fairly apparent. Juveniles are mainly whitish below with neatly dark streaks about the wing linings, breast, flanks and thighs, with bars on the axillaries and flight feathers. The tail of the juvenile has a broadly white tip and bars like adults but the ground color is a paler shade of gray.<ref name="Ferguson-Lees" /><ref name="Palmer" />
[[File:Cooper's hawk in Prospect Park (22513).jpg|thumb|left|A juvenile Cooper's hawk in Brooklyn, New York]]
Adults have eyes ranging from light orange to red, with males averaging darker in eye color, while those of juveniles are yellow.<ref name= Ferguson-Lees/> Among 370 breeding hawks from different parts of the range, 1-year-old males usually had light orange eyes and 1-year-old females usually yellow eyes. Meanwhile, males of 2 or more years old always had consistently darker eyes than the eyes of females of the same relative age, with most males of the age having largely either orange (40.4%) or dark orange (32.3%) eyes, while female eyes at this stage were light orange or lighter. From the second year, the eyes of Cooper's hawks may grow darker still but stop darkening shortly thereafter. 3-year or older males were found to have predominantly dark orange (37.3% vs 21.6% of similar age females), red (34.6% vs 3.3% of similar age females) or mid-orange (26.6% vs 55% of similar age females).<ref name= Rosenfield>Rosenfield R. N. & Bielefeldt, S. A. (1992). ''Reanalysis of Relationships among Eye Color, Age and Sex in the Cooper's hawk''. J. Raptor Res, 31(4), 313–316.</ref> For unclear reasons, far more adults in [[British Columbia]] and [[North Dakota]] (83% of males, 63% of females) had dark orange or red eyes (which also manifested at an earlier age in British Columbia) than mature hawks in [[Wisconsin]] (49% of males, 14% of females). Most females over 2 years old in Wisconsin were found to have light orange eyes.<ref name= Rosenfield2>Rosenfield, R. N., Bielefeldt, J., Rosenfield, L. J., Stewart, A. C., Murphy, R. K., Grosshuesch, D. A., & Bozek, M. A. (2003). ''Comparative relationships among eye color, age, and sex in three North American populations of Cooper's Hawks''. The Wilson Journal of Ornithology, 115(3), 225–230.</ref> The purpose of bright eye color in the hawks may be correlated to feeding stimulation of nestling hawks (i.e. darker orange or red objects may be more perceptible and tend to be pecked at more so than duller colors).<ref>Snyder, N. F., & Snyder, H. A. (1974). ''Function of eye coloration in North American accipiters''. Condor, 219–222.</ref> The eyes of this hawk, as in most predatory birds, face forward, enabling good depth perception for hunting and catching prey while flying at top speeds. Adults have greenish yellow ceres and have legs of orangish to yellow while these parts on juveniles are a paler hue, yellow-green to yellow.<ref name= Ferguson-Lees/><ref name= Brown/> 

The prebasic [[Molting|molt]] begins in late April–May and takes about 4 months. The female usually begins to molt about 7–10 days sooner than the male. Molts occur inward towards the body on the wing feathers. Tail molt may generally start with the middle tail feathers, proceeding posteriorly to the upper tail coverts, also starting with the median feathers on the scapulars.<ref name="Palmer" /><ref name="Henny">Henny, C. J., Olson, R. A., & Fleming, T. L. (1985). ''Breeding chronology, molt, and measurements of Accipiter hawks in northeastern Oregon''. Journal of Field Ornithology, 97–112.</ref> Up to 36% of juvenile feathers may be retained in the second pre-basic molt.<ref name="Pyle">Pyle, P. (2005). ''First-cycle molts in North American Falconiformes''. Journal of Raptor Research, 39:378–385.</ref> Arrested molt has been recorded in the late nesting period, often pausing after the third primary is molted. Molts tend to be halted especially when food supplies are down during the brooding stage, and may be resumed after the stress of feeding the brooding diminishes.<ref name="Palmer" /><ref name="Henny" /><ref name="Howell">Howell, S. N. G. (2010). ''Peterson Reference Guide to Molt in North American Birds''. Houghton Mifflin Harcourt Company, Boston, MA, USA.</ref>

===Size===
Cooper's hawks are fairly variable in size. There is usually minimal to no overlap in dimensions between the sexes, with females being considerably larger than males.<ref name= Palmer/> On average, she may be about 20% larger linearly and around 40% heavier (though can be up to 125% more massive).<ref name= Ferguson-Lees/> More westerly Cooper's hawks (roughly west of the [[Rocky Mountains]]) show slightly less pronounced [[sexual dimorphism]] than hawks of the species elsewhere.<ref name= Smith>Smith, J. P., Hoffman, S. W., & Gessaman, J. A. (1990). ''Regional Size Differences among Fall-Migrant Accipiters in North America''. Journal of Field Ornithology, 192–200.</ref> 

Sexual dimorphism in Cooper's hawks is most reliably measured by wing size, talon size, then body mass. Although there is some margin of error, within a given region dimensions of the two sexes never overlap in these regards (but may overlap marginally in tarsal and tail lengths).<ref name="Hoffman" /> In general terms, ''Astur'' and ''Accipiter'' species are among the most sexually dimorphic in size of all raptorial birds.<ref name="Reynolds">{{Cite journal | last=Reynolds | first=Richard T. | date=1972 | title=Sexual dimorphism in ''Accipiter'' hawks: A new hypothesis | journal=The Condor | volume=74 | issue=2 | pages=191–197 | doi=10.2307/1366283 | jstor=1366283 | url=https://sora.unm.edu/node/102162 }}</ref> Sexual dimorphism in ''Astur'' and ''Accipiter'' may be due to greater male efficiency through smaller size and resulting agility in food gathering for the family group. Meanwhile, the female may be better suited to the rigors of brooding (including perhaps most nest defense) due to her larger size, also allowing the sexes to compete less on the same food sources.<ref name="Snyder" /><ref name="Reynolds" /> 

Geographic variation in body size has also been found, with more easterly hawks tending to be rather larger on average than those found in western North America.<ref name="umich2000">Dewey, T. and V. Perepelyuk. (2000). [http://animaldiversity.ummz.umich.edu/site/accounts/information/Accipiter_cooperii.html ''Accipiter cooperii''], Animal Diversity Web. Accessed April 22, 2010.</ref><ref name="Mueller">Mueller, H. C., & Berger, D. D. (1981). ''Age, sex, and seasonal differences in size of Cooper's Hawks''. Journal of Field Ornithology, 52(2), 112–126.</ref> On the contrary, in the [[Southwestern United States|American southwest]], the species may reportedly reach its largest sizes but there is little evidence that these birds average distinctly larger than the large bodied individuals measured in the more northeasterly parts of the species' range in North America, from eastern [[North Dakota]] to [[New Jersey]].<ref name=BOW /><ref name="Whaley">Whaley, W. H., & White, C. M. (1994). ''Trends in geographic variation of Cooper's hawk and northern goshawk in North America: a multivariate analysis''. Western Foundation of Vertebrate Zoology.</ref> The size variation evidenced in Cooper's hawks is apparently the most pronounced of any of the three North American species of ''Astur''/''Accipiter''.<ref name="Smith" /> However, Cooper's hawks are one of an estimated 25% of studied bird species that do not appear to correspond to [[Bergmann's rule]] (i.e. being larger where living farther north) instead varying in size much more so by [[longitude]].<ref>Meiri, S., & Dayan, T. (2003). ''On the validity of Bergmann's rule''. Journal of biogeography, 30(3), 331–351.</ref> Furthermore, juveniles can differ somewhat in size, tending to be slightly lighter and smaller than older birds, but not infrequently averaging longer in tail and especially wing length.<ref name="Mueller" /><ref name="Rosenfield3">Rosenfield, R. N., Rosenfield, L. J., Bielefeldt, J., Murphy, R. K., Stewart, A. C., Stout, W. E., Driscoll, T.G. & Bozek, M. A. (2010). ''Comparative morphology of northern populations of breeding Cooper's Hawks''. The Condor, 112(2), 347–355.</ref> Total length of full-grown birds can vary from {{convert|35|to|46|cm|in|abbr=on}} in males and {{convert|42|to|50|cm|in|abbr=on}} in females.<ref name="Palmer" /><ref name="umich2000" /><ref name="allaboutbirds1" /> Wingspan may range from {{convert|62|to|99|cm|in|abbr=on}}, with an average of around {{convert|84|cm|in|abbr=on}}.<ref name="Palmer" /><ref name="HBW">White, C.M., Boesman, P. & Marks, J.S. (2020). ''Cooper's Hawk (Accipiter cooperii)''. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.</ref><ref name="Cartron">Cartron, J. L. E. (Ed.). (2010). ''Raptors of New Mexico''. UNM Press.</ref>
 
[[File:Hawk (28346062734).jpg|thumb|An adult Cooper's hawk illustrates its mid-sized frame and very long tail]]
Body mass, along with standard measurements, is much more frequently measured than total length or wingspan in different populations.<ref name= Palmer/> Museum specimens from the western United States averaged {{convert|280|g|oz|abbr=on}} in 48 males and {{convert|473|g|lb|abbr=on}} in 20 females, while those sourced from the eastern United States averaged {{convert|338|g|oz|abbr=on}} in 16 males and {{convert|566|g|lb|abbr=on}} in 31 females.<ref name= Friedmann>Friedmann, H. (1950). ''Birds of North and Middle America, Part 2''. U.S. National Museum Bulletin no. 50.</ref> Average weight of 104 male migrating hawks in [[Cedar Grove, Wisconsin]] was {{convert|342|g|oz|abbr=on}} (with adults averaging 4% heavier than juveniles), whilst the average of 115 females migrants was {{convert|518|g|lb|abbr=on}} (with adult averaging about 5.5% heavier than juveniles).<ref name= Mueller/> A different sample of Wisconsin Cooper's hawks reportedly averaged {{convert|327|g|oz|abbr=on}} in males (sample size 60) and {{convert|580.3|g|lb|abbr=on}} in females (sample size 57).<ref name= Rosenfield3/> At [[Cape May Point]], [[New Jersey]], weights were similar as in Wisconsin (although only hatching-year juveniles were apparently weighed), with averages of {{convert|339.2|and|347|g|oz|abbr=on}} in two samples of males and {{convert|518|and|530.3|g|lb|abbr=on}} in the two samples for females.<ref name= Pearlstine/><ref name= Smith/> Migrant hawks in the [[Goshute Mountains]] of [[Nevada]] were significantly lighter than the eastern ones at {{convert|269|g|oz|abbr=on}} in 183 first year males and {{convert|281|g|oz|abbr=on}} in 177 older males and {{convert|399|g|oz|abbr=on}} in 310 first year females and {{convert|439|g|oz|abbr=on}} in 416 older females.<ref name= Smith/> Weights were similar to the Goshutes in the [[Marin Headlands]], California where 50 males (all first-years) averaged {{convert|288|g|oz|abbr=on}} and 117 first-year females averaged {{convert|417|g|oz|abbr=on}}.<ref name= Smith/><ref name= Pitzer>Pitzer, S., Hull, J., Ernest, H. B., & Hull, A. C. (2008). ''Sex determination of three raptor species using morphology and molecular techniques''. Journal of Field Ornithology, 79(1), 71–79.</ref> Averaged between early and late summer, the average mass of males in [[Oregon]] was {{convert|280.7|g|oz|abbr=on}} and that of females was reported at {{convert|488.4|g|lb|abbr=on}}.<ref name= Henny/> The average weights of Cooper's hawks from Oregon was about 19.4% lower in males and 14.5% lower in females than those from Wisconsin but the Oregon hawks evidenced less seasonal variation in weight.<ref name= Henny/> In [[British Columbia]], males averaged {{convert|295.8|g|oz|abbr=on}} and females averaged {{convert|525.5|g|lb|abbr=on}} while in western and eastern North Dakota, males averaged {{convert|301.5|and|318.7|g|oz|abbr=on}} and females averaged {{convert|514.3|and|563.3|g|lb|abbr=on}}.<ref name= BOW/><ref name= Rosenfield3/> In northern Florida, males averaged {{convert|288|g|oz|abbr=on}} and females averaged {{convert|523|g|lb|abbr=on}}.<ref name= Millsap>Millsap, B. A., Breen, T. F., & Phillips, L. M. (2013). ''Ecology of the Cooper's Hawk in north Florida''. North American Fauna, 78(00), 1–58.</ref> In general, males may weigh anywhere from {{convert|215|to|390|g|oz|abbr=on}} and females anywhere from {{convert|305.8|to|701|g|lb|abbr=on}}, the lightest hawks generally being juveniles recorded from the Goshutes of Nevada, the heaviest known being adults from Wisconsin.<ref name= Hoffman>Hoffman, S. W., Smith, J. P., & Gessaman, J. A. (1990). ''Size of Fall-Migrant Accipiters from the Goshute Mountains of Nevada (Tamaño de migrantes otoñales (Accipitrinae) de las Montañas Goshute, Nevada)''. Journal of Field Ornithology, 201–211.</ref><ref name= Rosenfield4>Rosenfield, R. N., Bielefeldt, J., Haynes, T. G., Hardin, M. G., Glassen, F. J., & Booms, T. L. (2016). ''Body mass of female Cooper's Hawks is unrelated to longevity and breeding dispersal: Implications for the study of breeding dispersal''. Journal of Raptor Research, 50(3), 305–312.</ref>

Among standard measurements, the [[Wing chord (biology)|wing chord]] may vary from {{convert|214|to|252|mm|in|abbr=on}} in males and from {{convert|247|to|278|mm|in|abbr=on}} in females.<ref name= Ferguson-Lees/><ref name= Rosenfield5>Rosenfield, L. J. (2006). ''Comparative morphology among three northern populations of breeding Cooper's Hawks'' (Doctoral dissertation, University of Wisconsin—Stevens Point).</ref> Wing chord is generally commensurate with body mass, averaging largest in the heavier hawks of eastern North Dakota, where males averaged {{convert|232.6|mm|in|abbr=on}} and females {{convert|264.3|mm|in|abbr=on}}, and in Wisconsin, where males averaged {{convert|236.9|mm|in|abbr=on}} and females {{convert|267.1|mm|in|abbr=on}} (those from Cape May also being similar to those two samples). However, smaller, more westerly hawks such as those in the Goshute mountains, where males measured at a mean of {{convert|224.1|mm|in|abbr=on}} and females at a mean of {{convert|254.8|mm|in|abbr=on}}, and in British Columbia, with a male mean of {{convert|227|mm|in|abbr=on}} and female mean of {{convert|256.8|mm|in|abbr=on}}, were proportionately longer winged relative to their other body proportions.<ref name= BOW/><ref name= Rosenfield3/><ref name= Hoffman/> The tail of males may vary from {{convert|166|to|211|mm|in|abbr=on}} and that of females at {{convert|203|to|242|mm|in|abbr=on}}, consistently over {{convert|200|mm|in|abbr=on}} in females and averaging under {{convert|190|mm|in|abbr=on}} in males.<ref name= Ferguson-Lees/><ref name= Brown/><ref name= Hoffman/><ref name= Rosenfield5/> In [[Tibiotarsus|tarsus]] length, males may vary from {{convert|55.2|to|73|mm|in|abbr=on}}, with an average of {{convert|64.1|mm|in|abbr=on}} in museum specimens, and females from {{convert|62|to|76|mm|in|abbr=on}}, with an average of {{convert|71.1|mm|in|abbr=on}} in museum specimens.<ref name= Ferguson-Lees/><ref name= Friedmann/><ref name= Hoffman/><ref>{{cite web| url= http://www.royalbcmuseum.bc.ca/Natural_History/Bones/Tarsus/tarsus57.htm |title= ''Avian Osteology: Tarsometatarsus'' |website= RoyalBCMuseum.bc.ca| publisher= Royal British Columbia Museum Corporation | access-date= August 21, 2012}}</ref> The [[Beak|culmen]] may measure from {{convert|11.7|to|17.5|mm|in|abbr=on}} in males, averaging about {{convert|16|mm|in|abbr=on}}, and from {{convert|17.5|to|23|mm|in|abbr=on}} in females, averaging about {{convert|19|mm|in|abbr=on}}.<ref name= Friedmann/><ref name= Hoffman/><ref name= Rosenfield5/><ref>{{cite book| first1= Emmet Reid| last1= Blake |title=''Manual of Neotropical Birds'' |url=https://books.google.com/books?id=YP0AX3LW8jYC&pg=PA301 |access-date=August 21, 2012 |date=July 1, 1977 |publisher= University of Chicago Press |isbn=978-0-226-05641-8 |pages=301–}}</ref> The [[Claw|hallux claw]], the enlarged rear talon featured on nearly all accipitrids, may measure from {{convert|17|to|21.7|mm|in|abbr=on}} in males, averaging about {{convert|19.2|mm|in|abbr=on}}, and from {{convert|19.8|to|26.7|mm|in|abbr=on}} in females, averaging about {{convert|23.3|mm|in|abbr=on}}.<ref name= Hoffman/><ref name= Rosenfield5/> The footpad of Cooper's hawks may measure in males {{convert|61|to|70.2|mm|in|abbr=on}}, averaging {{convert|66|mm|in|abbr=on}} in 42, and in females {{convert|74.1|to|83.5|mm|in|abbr=on}}, averaging {{convert|76.8|mm|in|abbr=on}} in 23.<ref name= Whaley/> For unclear reasons, the smaller-bodied hawks found in British Columbia were found to be proportionately larger footed, median toe length between sexes of {{convert|37.3|mm|in|abbr=on}}, than the larger bodied ones in Wisconsin.<ref name= Feet>Rosenfield, R. N., Stewart, A. C., Stout, W. E., Sonsthagen, S. A., & Frater, P. N. (2020). ''Do British Columbia Cooper's Hawks Have Big Feet?'' British Columbia Birds, 30.</ref>

===Voice===
{{ Listen
| filename = Accipiter cooperii - Cooper's Hawk - XC74741.ogg
| title = Cooper's hawk vocalization
| description = A Cooper's hawk calling from an urban park in Minnesota
}}
Some authors have claimed that during breeding Cooper's hawks may utter well over 40 call variations, which would rank them as having among the most varied collection of calls recorded for any raptor. However, many such variations are probably quite subtle (marginal differences in harshness, clarity, tempo and volume) and other authors have diagnosed only four overall call types.<ref name= Palmer/><ref name= Meng>Meng, H. K. (1951). ''Cooper's Hawk, Accipiter cooperii''. Unpublished thesis, Cornell Univ., Ithaca, New York.</ref><ref name= Rosenfield6>{{Cite journal | last1=Rosenfield | first1=Robert N. | last2=Bielefeldt | first2=John | date=1991 | title=Vocalizations of Cooper's Hawks during the pre-incubation stage | journal=The Condor | volume=93 | issue=3 | pages=659–665 | doi=10.2307/1368197 | jstor=1368197 | url=https://www.researchgate.net/publication/268215450}}</ref> The typical call of a Cooper's hawk is a harsh, cackling yelp. This call may be translated as ''keh-keh-keh''..., males tending to have a higher pitched, less raspy and faster-paced voice than females.<ref name= Ferguson-Lees/><ref name= Brown/> 

However, some variants uttered by males were deeper than the female's version of said calls.<ref name="Fitch">Fitch, H. S. (1958). ''Home ranges, territories, and seasonal movements of vertebrates of the Natural History Reservation''. University of Kansas Publications Museum of Natural History, 11:63–326.</ref> A still more modulated and raucous version is given during the dawn chorus.<ref name="Brown" /> Some studies have indicated that pairs nesting in more deeply wooded areas may vocalize more frequently due to inferior sight lines.<ref name="Rosenfield6" /> However, hawks nesting in urban areas of [[Arizona]] do not seem to vocalize less than their rural nesting counterparts.<ref name="Estes">Estes, W. A., & Mannan, R. W. (2003). ''Feeding behavior of Cooper's Hawks at urban and rural nests in southeastern Arizona''. The Condor, 105(1), 107–116.</ref> There is perhaps some evidence that individual hawk's voices may become lower pitched with age.<ref name="Brown" /> When coming with food to the nest or while displaying during courtship, the male may let out a [[nighthawk]]-like ''kik'', apparently this call is more prevalent in pairs using thicker woods.<ref name=BOW /><ref name="Brown" /><ref name="Rosenfield6" /> Infrequently, females may utter the ''kik'' call as well, apparently when looking for her mate or gathering nesting materials.<ref name="Rosenfield6" /> Many soft calls have been recorded in intimate or "conversational" interactions, exclusively between breeding pairs and between mothers and their broods.<ref name="Ferguson-Lees" /><ref name="Palmer" /> 

The initial call of the young is a ''cheep'' or ''chirrp'', which by the time they are fledgling young alters to a penetrating hunger call, ''eeeeeeee-oo'' or ''tseeeee-ar'' (among different transliterations).<ref name="Ferguson-Lees" /><ref name=BOW /><ref name="Layne">Layne, J. N. (1986). ''Observations on Cooper's Hawk nesting in south central Florida''. Florida Field Naturalist, 14:85–112.</ref> The higher pitched calls of the young may even extend to females nesting within their first year while still in immature plumage.<ref name="Brown" /> Females have what is often thought of as their own hunger cry, ''whaaaa'', heard especially in poorer food areas, when the male appears.<ref name=BOW /><ref name="Estes" /> Nonetheless, the females ''whaaaa'' call has also been uttered in different contexts, such as during nest building and during a "postural bowing" display, and some authors inferred that it may be a means of communicating to the male that it is not dangerous for him to approach her (as ''Astur''/''Accipiter'' females can be dangerous to the much smaller males).<ref name="Meng" /><ref name="Rosenfield6" /><ref name="Rosenfield7">Rosenfield, R. N., & Bielefeldt, J. (1991). ''Undescribed bowing display in the Cooper's Hawk''. The Condor, 93(1), 191–193.</ref> Generally, Cooper's hawks are silent outside the breeding season.<ref name="Ferguson-Lees" /> Rarely, though, some males that appear to be isolated from any other hawks of their species have been known to call during winter.<ref name="Rosenfield8">Rosenfield, R. N. (2018). ''The Cooper's Hawk: Breeding Ecology & Natural History of a Winged Huntsman''. Hancock House Publishers.</ref>

===Confusion species===
[[File:Coopers Hawk From The Crossley ID Guide Eastern Birds.jpg|thumb|left|Composite image of Cooper's hawks for identification]]

''Accipiter'' and ''Astur'' species in North America are arguably the most vexing raptor to identify in the continent.<ref name= Crossley>Crossley, R., Liguori, J., & Sullivan, B. L. (2013). ''The Crossley ID Guide: Raptors''. Princeton University Press.</ref><ref name= Liguori>Liguori, J. (2005). ''Hawks from every angle: how to identify raptors in flight''. Princeton University Press.</ref><ref name= Clark>Clark. W.S. (1984). ''Field identification of Accipiters in North America''. Birding, 16: 251–263.</ref> The other two species in North America are the smaller [[sharp-shinned hawk]] (''Accipiter striatus'') and the larger [[American goshawk]] (''Astur atricapillus''). Compared to the other two species, Cooper's have an intermediate amount of feathering at top of the tarsus, as well as intermediate relative middle toe length and eye proportions, but have relatively the longest tail and the shortest wings of the three.<ref name= Palmer/> Cooper's and sharp-shinned hawk are very similar (sometimes considered almost identical) in plumage characteristics at all stages of development.<ref name= Ferguson-Lees/><ref name= Liguori/> Most Cooper's hawks are considerably larger than most sharp-shinned hawks.<ref name= Palmer/> Generally, Cooper's species is [[crow]]-sized, with the males about the size of a [[Fish crow|small crow]] and the females the size of a [[American crow|large crow]], while most sharp-shinned hawks are about the size of a large [[Steller's jay|jay]].<ref name= Brown/> Also in the hand, Cooper's hawks and sharp-shinned hawks may be fairly reliably distinguished by their sizes, with the smallest male Cooper's always being heavier and larger clawed than the largest female sharp-shinned hawk (with a 97–98% difference in dimensions of the wing and tail).<ref name= Smith/><ref name= Hoffman/> However, in the field, especially when hawks must be identified in at a distance or at unfavorable angles (such as when migrating) or at a brief glance (such as when hunting), even experienced [[birdwatcher]]s may not always be able to certainly distinguish the two species, especially female sharp-shins against the nearly similarly sized male Cooper's.<ref name= Crossley/><ref>Roberts, T. S. (1932). ''Manual for the identification of the birds of Minnesota and neighboring states''. U of Minnesota Press.</ref> The sharp-shinned hawk usually evidences a slimmer, slighter look, with more dainty features, and has relatively longer wings and a shorter and more squared tail with a much thinner white tip. Other slight differences may be noted in plumage via the sharp-shins lacking the capped appearance of adult Cooper's (being more hooded) and being generally slightly darker above. 

Juvenile sharp-shins, upon relatively leisurely study, can be seen to differ from juvenile Cooper's by having clearer supercilia, browner cheeks and less extensive whitish mottling above and also coarser streaking below extending more to belly.<ref name="Ferguson-Lees" /><ref name="Crossley" /> Bare parts, mostly distinguishable as well at close range, differ by the more centered and clearly relatively larger eyes and notably stick-like legs of the sharp-shins.<ref name="Ferguson-Lees" /><ref name="Liguori" /> However, often these features can often be difficult to impossible to discern when the hawks are seen in the wild.<ref name="Ferguson-Lees" /><ref name="Crossley" /><ref>Liguori, J. (2011). ''Hawks at a distance: identification of migrant raptors''. Princeton University Press.</ref> More distinctive in the field is the larger, more protruding head of the flying Cooper's hawks rather than the compact, rounded head of the sharp-shins which barely appear to exceed the leading edge of the wings in flight.<ref name="Crossley" /><ref name="Liguori" /><ref name="Clark" /><ref name="Dunne">Dunne, P., Sibley, D., & Sutton, C. (1988). ''Hawks in flight: the flight identification of North American migrant raptors''. Houghton Mifflin Harcourt (HMH).</ref> Sometimes Cooper's is considered to look like a "flying cross" in comparison to the sharp-shins. ''Accipiter'' and ''Astur'' hawks of all species are seen mostly flying with quick, consecutive wing beats and a short glide (sometimes abbreviated as "flap-flap-glide"), though the species may also soar as well.<ref>{{cite web |url=https://www.mbr-pwrc.usgs.gov/Infocenter/i3330id.html |title=''Cooper's hawk Accipiter cooperii'' |access-date=November 18, 2008 |author1=Robbins, C.S. |author2=Bruun, B. |author3=Zim, H.S. |date=July 3, 2008 |work=Patuxent Wildlife Research Center |publisher=USGS |archive-date=January 2, 2020 |archive-url=https://web.archive.org/web/20200102124816/https://www.mbr-pwrc.usgs.gov/Infocenter/i3330id.html }}</ref><ref>{{cite web|title= Cooper's Hawk Identification| publisher= Lab. of Ornithology, Cornell University| url= http://www.allaboutbirds.org/guide/coopers_hawk/id| website= allaboutbirds.org| access-date= August 21, 2012}}</ref> However, the sharp-shinned hawk has a more buoyant flight with faster wing beats than Cooper's and soars with flatter wings (although again variations in the field make these characteristics far from foolproof).<ref name="Crossley" /><ref name="Liguori" /><ref name="Dunne" />

[[File:Accipiter cooperii striatusDO1908P0203A.jpg|right|thumb|Comparison of a male Cooper's hawk (left) with [[Meadowlark|prey]] and a female [[sharp-shinned hawk]] (right) with [[Rose-breasted grosbeak|prey]]. Both prey items are about one third the weight of the respective hawks.]] 
As for the American goshawk, the smallest male is still usually "clearly" larger than most large female Cooper's hawks.<ref name= Ferguson-Lees/> In the Goshutes mountains, migrant male goshawks overlapped with female Cooper's hawks only in the length of the tail and the tarsus, with the body mass especially being quite distinct.<ref name= Hoffman/> In Oregon, male goshawks averaged no less than 34% more massive than female Cooper's hawks, however the footpad of Cooper's females was almost the same size (7% larger on average in the latter) as the male goshawks (these may be features adapted to procuring birds as prey more so as bird-hunting raptors tend to have more elongated foot morphology).<ref name= Henny/><ref>Fowler, D. W., Freedman, E. A., & Scannella, J. B. (2009). ''Predatory functional morphology in raptors: interdigital variation in talon size is related to prey restraint and immobilisation technique''. PLOS ONE, 4(11).</ref> Proportionately, goshawks have longer, broader wings, shorter tail and a generally more [[Buteo|''Buteo''-like]] form overall.<ref name= Ferguson-Lees/><ref name= Liguori/> Adult goshawks also have broad supercilia, pale gray color on the underside and a much darker [[Slate|coloring]] on the back. Given reasonable views, adult goshawks are very different looking and hard to mistake for any Cooper's hawk.<ref name= Palmer/> 

Meanwhile, the juvenile goshawk is much paler edged above than the smaller Cooper's, including a panel formed along larger wing coverts. Below, juvenile goshawks have heavier streaks of a darker brown color than juvenile Cooper's. Also, the banding on the tail is off-set on goshawks, creating a zigzag effect on the tail, unlike the even barring on the juvenile Cooper's.<ref name="Ferguson-Lees" /><ref name=BOW /> Again, though, female Cooper's and male goshawks can come close to the same size and the not dissimilar juvenile plumage of the two species can lead to regular misidentification, especially to those with less prior experience viewing the more scarce goshawk.<ref name="Crossley" /><ref name="Liguori" /><ref name="Dunne" /> The most reliable way to distinguish a large juvenile ''Accipiter''/''Astur'' in the field are the differing proportions of the two species, followed by the heavier streaking below and irregular tail banding of the goshawk.<ref name="Crossley" /><ref name="Clark" /> For Cooper's hawk, there may be a possible and marginal overlap with the [[bicolored hawk]] (''Astur bicolor'') in southern Mexico and Central America. The latter species of similar form and size but at all ages is generally unmarked with bars or streaks below, also with a more or less uniform mantle.<ref name="Ferguson-Lees" /><ref name="HBW" /> 

Vagrating migrant Cooper's hawks to [[Cuba]] may very rarely occur alongside another close relative, [[Gundlach's hawk]] (''Astur gundlachi''), which is quite similar in most aspects to Cooper's but is slightly larger with a darker hue about the back and the cap, a gray cheek, more dense and rich rufous color on the underside and wing panel in adults and darker and more heavy streaking in juvenile form.<ref name="Ferguson-Lees" /><ref name="HBW" /><ref name="Rodriguez-Santana">Rodríguez-Santana, F. (2010). ''Reports of Cooper's Hawks (Accipiter cooperii), Swainson's Hawks (Buteo swainsoni), and Short-tailed Hawks (Buteo brachyurus) in Cuba''. Journal of Raptor Research, 44(2), 146–150.</ref><ref>Garrido, O. H. (1985). ''Cuban endangered birds''. Ornithological Monographs, 992–999.</ref> 

More unlikely to be mistaken for a Cooper's hawk are some [[Buteoninae|buteonine hawks]] such as [[gray hawk]]s (''Buteo plagiatus''), [[roadside hawk]]s (''Rupornis magnirostris'') (in Mexico and points south) and [[broad-winged hawk]]s (''Buteo platypterus'') which are all similar in size to Cooper's as well as the slightly larger [[red-shouldered hawk]] (''Buteo lineatus''). Even the most similar buteonine hawks have notably different proportions than a Cooper's hawk, possessing relatively much longer wings and a much shorter tail. Given reasonable views, all such species are fairly to extremely different in plumage even in juvenile form.<ref name="Ferguson-Lees" /><ref name="Crossley" />

==Distribution and habitat==
[[File:Juvenile Cooper&#039;s Hawk.jpg|thumb|A juvenile Cooper's hawk making use of a temporary perch in the open]]

Cooper's hawk's breeding range extends from southern Canada to northern Mexico. In southern Canada, they breed (but do not normally winter) in the southerly parts of the [[Provinces and territories of Canada|provinces]] of [[British Columbia]], Alberta, [[Saskatchewan]], Manitoba, [[Ontario]], Quebec to extreme southwestern [[Nova Scotia]].<ref>{{Cite web|title=Cooper's Hawk Facts – NatureMapping|url=http://naturemappingfoundation.org/natmap/facts/coopers_hawk_712.html#:~:text=Range%20/%20Habitat:%20The%20Cooper%27s%20Hawk,the%20United%20States%20and%20Mexico|access-date=June 3, 2021|website=naturemappingfoundation.org}}</ref> They reach their northerly limits as a breeder roughly in [[Jasper National Park]] and [[Cedar Lake (Manitoba)|Cedar Lake, Manitoba]].<ref name="iucn status 13 November 2021" /><ref name= Ferguson-Lees/><ref>Ridgely, R. S., Allnutt, T. F., Brooks, T., McNicol, D. K., Mehlman, D. W., Young, B. E., & Zook, J. R. (2003). ''Digital distribution maps of the birds of the Western Hemisphere''.</ref> Cooper's hawks live almost throughout the [[contiguous United States]], excepting some parts of the southern [[Great Plains]], as well as perhaps a bit of northwestern [[Maine]] and northernmost [[Montana]]. Their breeding range terminates just before the southern part of [[Gulf Coast]] states, [[south Florida]], the southern tip of [[Texas]] and all but inland northwestern Mexico.<ref name="iucn status 13 November 2021" /><ref name= Sauer>Sauer, J. R., Link, W. A., Fallon, J. E., Pardieck, K. L., & Ziolkowski Jr, D. J. (2013). ''The North American breeding bird survey 1966–2011: summary analysis and species accounts''. North American Fauna, 79(79), 1–32.</ref> 

Their Mexican breeding range consists of northern [[Baja California]], the mountains from eastern [[Sonora]] and [[Chihuahua (state)|Chihuahua]] to [[Durango]], also recently in northern [[Coahuila]], formerly east into [[Nuevo Leon]] and south to [[Michoacán]] and possibly still in [[Guerrero]].<ref>Howell, S. N., & Webb, S. (1995). ''A guide to the birds of Mexico and northern Central America''. Oxford University Press.</ref><ref>Miller, A. H. (1955). ''The avifauna of the Sierra del Carmen of Coahuila, Mexico''. The Condor, 57(3), 154–178.</ref> In [[Oaxaca]], records show that the species has been recorded year-around with the first confirmed breeding reported in 2001.<ref>Hunn, E. S., Vásquez, D. A., & Escalante, P. (2001). ''Birds of an Juan Mixtepec, District of Miahuatlan, Oaxaca, Mexico''. Cotinga, 16, 14–26.</ref><ref>Forcey, J. M. (2001). Breeding of Cooper's Hawk (Accipiter cooperii) in Oaxaca, Mexico. Huitzil, Revista Mexicana de Ornitología, 2(2), 21–23.</ref> In winter, they are found up to the southern half of [[Washington (state)|Washington]], the southern two-thirds of [[Idaho]] and [[Wyoming]], southern [[South Dakota]], the southern parts of [[Minnesota]], [[Wisconsin]] and [[Michigan]], extreme southwestern Ontario, southwestern and southeastern New York and [[New England]] up through all but northwestern [[Massachusetts]] and to the southeastern part of [[New Hampshire]].<ref name="iucn status 13 November 2021" /><ref name="Ferguson-Lees" /> In winter they range regularly throughout the parts of the southern United States where they do not breed, such as all Gulf Coast areas and in [[south Florida]].<ref name="iucn status 13 November 2021" /><ref name="Palmer" /> Wintering Cooper's hawks are common through essentially all parts of Mexico, becoming less regular around [[Guatemala]] and isolated spots of the border of [[Honduras]] and [[Nicaragua]], where the species is considered "infrequent but regular" as well as in central and southern [[Costa Rica]] and perhaps northern [[Panama]].<ref name="iucn status 13 November 2021" /><ref name="globalraptors1">Global Raptor Information Network. (2010). [http://www.globalraptors.org Species account: Cooper's Hawk Accipiter cooperii].</ref><ref>McCrary, J. K., Arendt, W. J., Chavarría, L., López, L. J., Somarriba, P. A., Boudrault, P. O., Cruz, A.L., Muñoz, F.J. & Mackler, D. G. (2009). ''A contribution to Nicaraguan ornithology, with a focus on the pine-oak ecoregion''. Contina, 31, 89–95.</ref><ref>Sandoval, L., & Sánchez, J. E. (2012). ''Lista de aves de Costa Rica. Elaborada por la Unión de Ornitólogos de Costa Rica''.</ref><ref>Garrigues, R., & Dean, R. (2014). ''The Birds of Costa Rica: A Field Guide''. Cornell University Press, Ithaca, NY, USA.</ref><ref>Ridgely, R. S., & Gwynne, J. (1989). ''A Guide to the Birds of Panama, with Costa Rica, Nicaragua, and Honduras. second edition''. Princeton University Press, Princeton, NJ, USA.</ref> Vagrants have been recorded in [[Colombia]].<ref name="Henny2">Henny, C. J. (1990). ''Wintering Localities of Cooper's Hawks Nesting in Northeastern Oregon (Lugares en Donde Pasan el Invierno Individuos de Accipiter cooperii que Anidan en el Noreste de Oregon)''. Journal of Field Ornithology, 104–107.</ref> There are several cumulative records of Cooper's hawks also appearing in [[Cuba]] at times of migration but generally the species is still considered a vagrant rather than a regularly occurring species there.<ref name="Rodriguez-Santana" /><ref name="Breman" />

===Habitat===
Cooper's hawks tend to occur in various types of [[temperate deciduous forest]] and [[Temperate broadleaf and mixed forest|mixed forest]].<ref name= Ferguson-Lees/> They are also adaptable in all seasons to [[Montane ecosystems|forested mountainous regions]], especially [[foothills]]. The species may further make itself at home in some pure [[Pinophyta|conifer]] forest, including the extreme southern part of the [[taiga]] but also in many parts of the west.<ref name= Cartron/><ref name= Garner>Garner, H. D. (1999). ''Distribution and habitat use of Sharp-shinned and Cooper's hawks in Arkansas''. Journal of Raptor Research, 33(4), 329–332.</ref><ref name= Kennedy>Kennedy, P. L. (1988). ''Habitat characteristics of Cooper's Hawks and Northern Goshawks nesting in New Mexico''. In ''Proceedings of the Southwestern Raptor Management Symposium and Workshop'' (R. Glinski, B. G. Pendleton, M. B. Moss, B. A. Millsap, and S. W. Hoffman, Editors). National Wildlife Federation, Washington, DC, USA. pp. 218–227.</ref><ref>Haney, A., Apfelbaum, S., & Burris, J. M. (2008). ''Thirty years of post-fire succession in a southern boreal forest bird community''. The American Midland Naturalist, 159(2), 421–433.</ref> The species can habituate favorably while breeding to various kinds of open [[woodland]]s, including small [[woodlot]]s, [[riparian]] woodlands in [[Semi-arid climate|dry country]], [[pinyon pine|pinyon]] woodlands, [[Agriculture|farmlands]] and [[floodplain]]s.<ref name= Ferguson-Lees/><ref name="globalraptors1"/><ref>Smith, E. L., Hoffman, S. W., Stahlecker, D. W., & Duncan, R. B. (1996). ''Results of a raptor survey in southwestern New Mexico''. J. Raptor Res, 30(4), 183–188.</ref><ref name= Rosenfield10>Rosenfield, R. N., Bielefeldt, J., Anderson, R. K., & Papp, J. M. (1991). ''Status reports: accipiters''. In ''Proceedings of Midwest Raptor Management Symposium Workshop''. Nat. Wildl. Fed., Washington, DC (pp. 42–49).</ref> In fact, some authors felt the species increased locally in wooded parts of the [[Rocky Mountains]] after human [[habitat fragmentation]] of once continuous woodland areas.<ref name= Palmer/> Adaptability to forest fragmentation has also been reported in other parts of the range.<ref>Rosenfield, R. N., Morasky, C.M., Bielefeldt, J. & Loope, W.L. (1992). ''Forest fragmentation and island biogeography: a summary and bibliography''. National Park Service, Natural Resources Publications Office.</ref>

In denser forest areas, these hawks tend to prefer easy access to [[Woodland edge|edges]], [[Clearing (geography)|clearings]], [[Dirt road|roads]] and [[Freshwater ecosystem|waterways]].<ref name= Ferguson-Lees/><ref name= Palmer/><ref name= Reynolds2>Reynolds, R. T., Meslow, E. C., & Wight, H. M. (1982). ''Nesting habitat of coexisting Accipiter in Oregon''. The Journal of Wildlife Management, 124–138.</ref> For example, average distance between waterways and nests in Wisconsin and Utah was {{convert|66.1|and|224|m|ft|abbr=on}}, respectively.<ref name= Rosenfield9>Rosenfield, R. N., & Anderson, R. K. (1983). ''Status of the Cooper's Hawk in Wisconsin''. Bureau of Endangered Resources, Wisconsin Department of Natural Resources.</ref><ref name= Hennessy>Hennessy, S. P. (1978). ''Ecological relationships of accipiters in northern Utah-with special emphasis on the effects of human disturbance''. M.S. thesis, Utah State Univ., Logan, Utah.</ref> However, in the [[Appalachians]], there seemed to no detectable preference for access to water.<ref name= Titus>Titus, K., & Mosher, J. A. (1981). ''Nest-site habitat selected by woodland hawks in the central Appalachians''. The Auk, 98(2), 270–281.</ref> Forest edges, in particular, tend to be key as these are peak hunting grounds for these hawks.<ref>Millsap, B. A., Madden, K. Murphy, R. K. & Campbell, D. (2012). ''Demography and Population Dynamics of Cooper's Hawks in Albuquerque, New Mexico, with an Emphasis on Non-breeding Adult Floaters: Annual Progress Report, Year Two''.</ref><ref name= Fischer>Fischer, D. L. (1986). ''Daily activity patterns and habitat use of coexisting Accipiter hawks in Utah''. Ph.D. dissertation, Brigham Young University, Provo, UT, USA.</ref> Cooper's hawks usually occur at elevations from sea-level to {{convert|2500|m|ft|abbr=on}}, more infrequently up to {{convert|3000|m|ft|abbr=on}}. In the American southwest and northwestern Mexico, they are commonly considered a bird of wooded foothills, often dwelling above {{convert|1000|m|ft|abbr=on}}.<ref name= Ferguson-Lees/><ref name= Howell/> 

Although they often live in areas where deciduous trees are predominant, almost throughout the range they are often attracted to stands of conifers, which, due to their density, provide more extensive shelter and perhaps a more sturdy nesting site.<ref name=BOW /> Therefore, in areas such as Massachusetts and Wisconsin, they most often used stands of [[Pinus strobus|white pines]] (''Pinus strobus'').<ref name="Bent" /><ref name="Rosenfield9" /> Additional Wisconsin studies showed that exotic conifer stands now support many Cooper's hawks even where native woodland is available.<ref name="Booms">Rosenfield, R. N., Bielefeldt, J., Sonsthagen, S. A., & Booms, T. L. (2000). ''Comparable reproductive success at conifer plantation and non-plantation nest sites for Cooper's Hawks in Wisconsin''. The Wilson Journal of Ornithology, 112(3), 417–421.</ref> Tall, native deciduous tree stands may still be used extensively elsewhere, i.e. [[Fagus grandifolia|American beeches]] (''Fagus grandifolia'') in New York (nearly 40% of nest trees used) and [[oak]]s in [[Maryland]] (60% of trees used as nests).<ref name=BOW /> This species often prefers fairly mature forest, i.e. in two different areas of [[Oregon]], Cooper's hawks preferred areas with trees of 30–60 years old (and 656 trees per ha) and 50–70 years old (and 1159 trees per ha), respectively.<ref name="Reynolds2" /> On average, the number of trees per hectare in [[Arkansas]] were found to be 935.7.<ref name="Garner" /> Canopy coverage is key to nesting Cooper's hawks, needing to be at minimum about 55–70%, averaging 55% in Wisconsin and 69.8% in Arizona.<ref name="Trexel" /><ref name="James">James, R. D. (1984). ''Habitat management guidelines for Ontario's forests nesting accipiters, buteos and eagles''.</ref><ref name="Boal">Boal, C. W., & Mannan, R. W. (1998). ''Nest-site selection by Cooper's Hawks in an urban environment''. The Journal of wildlife management, 864–871.</ref>

[[File:Cooper&#039;s hawk in snow whitehurst-brown divide (16560709775).jpg|thumb|left|Cooper's hawk are regular in wintery, snowy areas in the cooler months]]
More so than breeding habitat, wintering habitat seems to be highly opportunistic. They may be found in any environment with some trees, including [[Woodland|open wood]]s, parkland and [[Shrubland|scrub areas]].<ref name= Ferguson-Lees/><ref name= BOW/> In Central America, wintering Cooper's hawks have been recorded in unusual habitats such as stunted [[cloud forest]] and treeless montane [[grassland]].<ref name= Ferguson-Lees/><ref>Stiles, F. G., & Skutch, A. F. (1989). ''Guide to the birds of Costa Rica''. Comistock.</ref> In most parts of the range, Cooper's hawks have shown to be somewhat adaptive to all gradients of [[Land development|human development]], including urbanized areas and can even nest in many cities.<ref name="globalraptors1"/><ref name= Stahlecker>Stahlecker, D. W. & Beach, A. (1979). ''Successful nesting by Cooper's Hawks in an urban environment''. Inland Bird Banding News, 51:56–57.</ref><ref name= Murphy>Murphy, R. K., Gratson, M.W., & Rosenfield, R. N. (1988). ''Activity and habitat use by a breeding male Cooper's Hawk in a suburban area''. Journal of Raptor Research, 22:97–100.</ref> They were once thought to be averse to cities and towns, but are now fairly common urban and suburban birds even when nesting. The species may even making use of isolated trees in suburbs, [[industrial park]]s and [[Strip mall|strip]] and shopping malls though large [[urban park]]s and other [[Peri-urbanisation|available wooded habitat]] is usually preferred in such areas when nesting.<ref name= Palmer/><ref name= BOW/><ref name= Beebe>Beebe, F. L. (1974). ''Field studies of the Falconiformes of British Columbia: vultures, hawks, falcons, eagles''. Victoria: Occas. Pap. Brit. Columbia Prov. Mus. No. 17.</ref><ref name= Stout>Stout, W. E. & Rosenfield, R.N. (2010). ''Colonization, growth, and density of a pioneer Cooper's Hawk population in a large metropolitan environment''. Journal of Raptor Research, 44:255–267.</ref> Cities provide plenty of prey species such as [[Columbidae|pigeons and doves]] and [[invasive species]] of bird for Cooper's hawk to prey on.<ref name="allaboutbirds1"/> Evidence from a well-studied population in the city of [[Tucson]], [[Arizona]] shows that Cooper's hawks are now considerably more common within the city than elsewhere in the surrounding regions.<ref>Mannan, R. W., Boal, C. W., Burroughs, W. J., Dawson, J. W., Estabrook, T. S., & Richardson, W. S. (2000). ''Nest sites of five raptor species along an urban gradient''. In ''Raptors at risk: proceedings of the V world conference on birds of prey and owls''. World Working Group on Birds of Prey and Owls, Berlin, Germany (pp. 447–453).</ref> Despite the success of Cooper's hawks in Tucson, attempts to find breeding activity in [[Phoenix, Arizona|Phoenix]] and [[Casa Grande, Arizona|Casa Grande]] were unsuccessful, it is thought that the ambient temperature was too high or beyond thermal tolerance levels.<ref>Ward, M. S., & Mannan, R. W. (2011). Habitat model of urban-nesting Cooper's Hawks (Accipiter cooperii) in southern Arizona. The Southwestern Naturalist, 56(1), 17–23.</ref> Although more adaptable in habitat than the sharp-shinned hawk, studies from [[Pennsylvania]] have indicated that the species still more often than not prefers sizeable tracts of woodland for breeding and migrating to fragmented, developed areas.<ref name= Goodrich>Goodrich, L.J. (2010). [http://udini.proquest.com/view/stopover-ecology-of-autumn-goid:816918518/ ''Stopover ecology of autumn-migrating raptors in the central Appalachians''] {{Webarchive |url=https://web.archive.org/web/20131029202634/http://udini.proquest.com/view/stopover-ecology-of-autumn-goid:816918518/ |date=October 29, 2013}}. PhD dissertation, Pennsylvania State University, State College, PA</ref> Similarly, in [[Tennessee]], it was found for wintering Cooper's hawks that forested areas were 73% of the habitats used, which is far more prevalent than woodland available in the environs (with only 46% remaining wooded).<ref name= Lake>Lake, L. A., Buehler, D. A., & Houston, A. E. (2002). ''Cooper's Hawk non-breeding habitat use and home range in southwestern Tennessee''. In ''Proceedings of the Annual Conference of the Southeastern Association of Fish & Wildlife Agencies (SEAFWA)'', Tallahassee (Vol. 56, pp. 229–238).</ref>

==Behavior==
[[File:Cooper&#039;s Hawk bathing on a city street (47930519353).jpg|thumb|right|A young Cooper's hawk makes use of a large roadside puddle as a bath]]

Cooper's hawk is a typical ''Astur'' in all respects.<ref name= Ferguson-Lees/> This species tends to be active earlier in the morning than sharp-shinned hawks and is generally much more likely to be active in the morning than in the afternoon.<ref>Lang, S. D., Mann, R. P., & Farine, D. R. (2019). ''Temporal activity patterns of predators and prey across broad geographic scales''. Behavioral Ecology, 30(1), 172–180.</ref> These hawks may readily take to conifers to [[Bird#Resting and roosting|roost]], generally sleeping with their heads tucked in.<ref name= Ferguson-Lees/><ref name= Murphy/> During daylight hours, they tend to [[Preening (bird)|preen]] while sitting on a perch about 11 times a day, and may take about 1–20 minutes to do so.<ref name= Meng/> When attaining water to drink, Cooper's hawks appear to prefer to come to relatively secluded waterways.<ref>Stone, K., & Ramsey, A. (2014). ''Raptor Use of Water Sources as Documented via a Remote Camera Network''. Intermountain Journal of Sciences, 20(4), 110.</ref> In more [[arid]] regions, Cooper's hawks may seek out artificial [[body of water|bodies of water]] to drink from (especially in passage).<ref>Lynn, J. C., Rosenstock, S. S., & Chambers, C. L. (2008). ''Avian use of desert wildlife water developments as determined by remote videography''. Western North American Naturalist, 68(1), 107–112.</ref> Although a rare behavior, there are now several records of juvenile hawks of the species [[Prone position|proning]] wherein they lie on their backs along a branch (or rarely the ground), apparently as a form of [[Sunning (behaviour)|sunning]].<ref name= Sobolik>Rosenfield, R. N. & Sobolik, L.E. (2014). ''Proning behavior in Cooper's Hawks (Accipiter cooperii)''. Journal of Raptor Research, 48:294–297.</ref> Cooper's hawks may come to walk on ground to gather nesting materials as well as to hunt.<ref name= Rosenfield11>Rosenfield, R. N., Bielefeldt, J. & Cary, J. (1991). ''Copulatory and other pre-incubation behaviors of Cooper's Hawks''. Wilson Bulletin, 103:656–660.</ref> Cooper's hawks have a well-developed muscle mass that powers their flight, especially helping with acceleration during hunts and when carrying heavy prey. However, some other non-raptorial birds may have similar muscularity relative to their mass, such as the [[Canada goose]] (''Branta canadensis'') and even [[pied-billed grebe]]s (''Podilymbus podiceps''), and these ample muscle masses may be correlated with [[Bird migration|migratory]] (rather than hunting) behavior.<ref name= Marsh>Marsh, R. L. & Storer, R.W. (1981). ''Correlations of flight-muscle size and body mass in Cooper's Hawk: a natural analogue of power training''. Journal of Experimental Biology, 91:363–368.</ref> Cooper's hawks have been recorded as engaging in an exaggerated, [[nighthawk]]-like flight in non-courtship circumstances, such as during migration or by recent fledglings.<ref name= Layne/><ref>Berger, D. D. (1957). ''Peculiar type of flight in Cooper's Hawks''. Wilson Bulletin 69:110–111.</ref> During the late nesting stage, parent Cooper's hawks were recorded during daylight in Utah to engage in soaring flight 8.4% for males and 8.1% of the time for females with a further 6.4% and 2.8% of the time in different kinds of flights, perching the remainder of the time (about 2–6 minutes at each perch interspersed with brief flights).<ref name= Fischer/> Another study found 13.7% and 10.7% of daylight at this later breeding stage to be in flight, the rest of time perching, with occasional inactive perching spells of around 15–40 minutes. However, that inactivity could last up to 5 hours during heavy rainfall.<ref>Kennedy, P. L., & Gessaman, J.A. (1991). ''Diurnal resting metabolic rates of accipiters''. Wilson Bulletin, 103:101–105.</ref> Breeding adults generally engage in agonistic behavior when an interloper of their sex is present; 11 responses showed that males responses consisted 64% of the provocations, 9% of the time by females and both members 27% of the time.<ref name= Boal2>Boal, C. W. (2001). ''Agonistic behavior of Cooper's Hawks''. Raptor Research 35:253–256.</ref> Frequent aggressive interactions were recorded between females, often yearling and second year vs older females.<ref name= Lien>Lien, L. A., Millsap, B. A., Madden, K., & Roemer, G. W. (2015). ''Male brood provisioning rates provide evidence for inter‐age competition for mates in female Cooper's Hawks Accipiter cooperii''. Ibis, 157(4), 860–870.</ref> Cooper's hawk's threat display appears to consist of them lowering their heads, raising their "crest" (capital tract), stretching out their wings, spreading the tail and engaging in vocalizations.<ref name=BOW/> Stress levels, as indicated by a study of [[corticosterone]] levels, were considered quite high when hawks are being handled by researchers, particularly in males (indicating that they experience higher levels of stress than females).<ref>Rogers, H. M., Bechard, M. J., Kaltenecker, G. S., & Dufty, A. M. (2010). ''The adrenocortical stress response in three North American accipiters during fall migration''. Journal of Raptor Research, 44(2), 113–119.</ref> Cooper's hawk is subject to frequent [[Mobbing (animal behavior)|mobbing]] by various birds and some mammals, with good cause, but evidence shows that even main prey types like [[Jay (bird)|jays]] will sometimes shy away from engaging in full-fledged mobbing of a Cooper's, perhaps due to the risk in closely approaching this very agile predator, which can in an instant suddenly turn and kill a member of the mob. Therefore, less dangerous hawks such as ''Buteos'' are mobbed more vigorously than the more dangerous Cooper's. Many potential prey will confine their response to a hawk of this species to vocal scolding and/or attempt escape before an attack occurs.<ref>Hamerstrom, F. (1957). ''The influence of a hawk's appetite on mobbing''. The Condor, 59(3), 192–194.</ref><ref>Dahl, J. A., & Ritchison, G. (2018). ''Responses of Blue Jays (Cyanocitta cristata) to raptors that differ in predatory threat''. Avian Biology Research, 11(3), 159–166.</ref><ref>Commons, K. A. (2017). ''Mobbing behavior in Wild steller's jay (Cyanocitta stelleri)''. Thesis, Humboldt State University.</ref>

===Migration===
[[File:Cooper&#039;s Hawk (45354526355).jpg|thumb|The distinctive long-tailed, large headed form of Cooper's hawk in flight; short wings, seen when flapping, are also characteristic.]]

Like a majority of diurnal birds of prey in the [[Northern Hemisphere]], Cooper's hawk is a [[Bird migration|partial migrant]]. They tend to be most migratory in the north and largely to partially sedentary elsewhere.<ref name= Ferguson-Lees/><ref name= Palmer/> With individual exceptions, hawks of the species largely migrate out of nearly all of their range in southern Canada as well as cooler parts of the [[Pacific Northwest]], essentially all of [[Montana]] and northern parts of surrounding states, the [[Dakotas]] (but for southern [[South Dakota]]), the northern parts of the [[Great Lakes region|Great Lake]] states, northern New York and much of [[New England]].<ref name="iucn status 13 November 2021" /><ref name= Ferguson-Lees/> Despite being classed as sedentary, banding studies have revealed that many Cooper's hawks south of the typical migratory populations engage in some variety of seasonal winter movements.<ref name= Goodrich2>Goodrich, L. J., Farmer, C.J., Barber, D.R., & Bildstein, K.L. (2012). ''What banding tells us about the movement ecology of raptors''. Journal of Raptor Research, 46: 27–35.</ref> Migrants in the [[Florida Keys]] were determined via [[Stable isotope ratio|stable isotopes]] to have originated from [[mid-Atlantic states]] and the southeastern United States both (largely) south of the typical migratory range.<ref>Meehan, T. D., Lott, C. A., Sharp, Z. D., Smith, R. B., Rosenfield, R. N., Stewart, A. C., & Murphy, R. K. (2001). ''Using hydrogen isotope geochemistry to estimate the natal latitudes of immature Cooper's Hawks migrating through the Florida Keys''. The condor, 103(1), 11–20.</ref> While females in the urban areas of [[Tucson]] were sedentary (99%), about 6% of the females outside of the urban areas did not remain on their breeding grounds during winter.<ref name= Recruitment>Millsap, B. A. (2018). ''Female recruitment in an urban subpopulation of Cooper's Hawks (Accipiter cooperii) in central New Mexico''. PhD dissertation, New Mexico State University. Las Cruces, NM, USA.</ref> In [[British Columbia]], many adults are non-migratory but juveniles do tend to migrate.<ref name= Meehan>Meehan, T. D., Rosenfield, R. N., Atudorei, V. N., Bielefeldt, J., Rosenfield, L. J., Stewart, A. C., Stout, W.E. & Bozek, M. A. (2003). ''Variation in hydrogen stable-isotope ratios between adult and nestling Cooper's Hawks''. The Condor, 105(3), 567–572.</ref> From the Great Lakes region in particular, migrants appear to disperse in multiple directions to the south.<ref name= Palmer/><ref>Stout, W. E., Rosenfield, R.N. & Bielefeldt, J. (2008). ''Wintering location of a Wisconsin Cooper's Hawk and impact of digital photography on wildlife research''. Passenger Pigeon, 70: 373–379.</ref> Multi-directional movements, even to the north as well as potentially any other direction, are more common than previously thought in this and other migratory raptors, which has been previously described as "inefficient and indirect method of 'homing'".<ref>Mueller, H. C., & Berger, D. D. (1969). ''Navigation by hawks migrating in spring''. The Auk, 86(1), 35–40.</ref> However, reaching regions where appropriate habitat and prey is available is probably far more significant in seasonal movements to birds of prey than climatic concerns.<ref name= Palmer/><ref name= Hoffman2>Hoffman, S. W., Smith, J. P., & Meehan, T. D. (2002). ''Breeding grounds, winter ranges, and migratory routes of raptors in the mountain west''. Journal of Raptor Research, 36(2), 97–110.</ref> Fairly strong evidence has been found of habitual northbound migration by Cooper's hawks from [[Central California|Central]] and [[Southern California]], usually over fairly short distances, often less than {{convert|320|km|mi|abbr=on}}. However, the three longest distance movements from southern California were all northbound, i.e. {{convert|616|to|993|km|mi|abbr=on}}.<ref name= Meehan/><ref name= Bloom>Bloom, P. H., McCrary, M. D., Papp, J. M., & Thomas, S. E. (2017). ''Banding Reveals Potential Northward Migration of Cooper's Hawks from Southern California''. Journal of Raptor Research, 51(4), 409–416.</ref> Cooper's hawks originating from [[Northern California]] do generally migrate south, mostly wintering in Mexico though sometimes covering up to {{convert|1637|km|mi|abbr=on}} to Central America.<ref name= Bloom/> In [[Lansing, Michigan]], evidence has been found of individual Cooper's hawks being annually devoted to the same wintering grounds, presumably due to their high quality.<ref>Sanz, J. J., Moreno, J., Merino, S., & Tomas, G. (2004). ''Some Evidence of Winter Site Fidelity in Cooper's Hawks''. Iberia, 61, 187–196.</ref>

Migratory movements in the autumn are generally between late August to mid-October, peaking at the end of September and beginning of October in the [[Eastern United States|east]], but sometimes migration extend into November.<ref name= Palmer/><ref name= Mueller2>Mueller, H. C., Mueller, N. S., Berger, D. D., Allez, G., Robichaud, W., & Kaspar, J. L. (2000). ''Age and sex differences in the timing of fall migration of hawks and falcons''. The Wilson Bulletin, 214–224.</ref> Meanwhile, spring northward migration may be any time from the end of February to May, with the last ones leaving Mexico in April and very late individuals were passing over [[south Texas]] in late May.<ref name= Ferguson-Lees/><ref name= Palmer/> Generally, spring migration is more dispersed and less consistent than fall migration.<ref name=BOW/> There is evidence from the [[Great Lakes]] region that spring migration is occurring sooner due to [[Global warming|warming temperatures]] in recent years.<ref>Sullivan, A. R., Flaspohler, D. J., Froese, R. E., & Ford, D. (2016). ''Climate variability and the timing of spring raptor migration in eastern North America''. Journal of Avian Biology, 47(2), 208–218.</ref> Passage appears to be timed to coincide with that of their main prey, medium-sized birds.<ref name= Palmer/> In migration, first-year juveniles precede two-year-old hawks which themselves precede adults when moving south in fall. Furthermore, females of all ages tend to migrate sooner and spend longer in winter quarters than like-age males, the latter staying relatively north and traveling back again earlier.<ref name= Ferguson-Lees/><ref name= Mueller2/><ref name= Hull>Hull, J. M., Pitzer, S., Fish, A. M., Ernest, H. B., & Hull, A. C. (2012). ''Differential migration in five species of raptors in central coastal California''. Journal of Raptor Research, 46(1), 50–56.</ref> The sharp-shinned hawk (despite the even more dimorphic migration times between sexes) showed no strong difference in distance on migration between the sexes, unlike female Cooper's which sometimes can move considerably further than males.<ref name= Goodrich2/> At regular western migration sites, the average difference of passage timing for Cooper's hawks of the earlier females and later males of like-age was five days.<ref name= DeLong>DeLong, J., & Hoffman, S. W. (1999). ''Differential autumn migration of Sharp-shinned and Cooper's hawks in western North America''. The Condor, 101(3), 674–678.</ref> In the [[Marin Headlands]], migration of the sexes differed by 6 days in juvenile, first-year females and males and by 11 days in older females and males.<ref name= Hull/> Like other species of ''Accipiter'' or ''Astur'' (but unlike [[falcon]]s), Cooper's appear to not start moving until day is warmer and [[thermal]]s can be used.<ref name= Palmer/> During migration they favor [[mountain ridge]]s and [[coast]]lines, which coincide with migratory raptors routes in general.<ref name=BOW/> This species can seem to cross some bodies of water unlike most sharp-shinned hawks but seldom do so over wide bodies of water.<ref name= Palmer/> However, they have been seen to turn up in such oceanic vicinities as the [[Florida Keys]] and [[Cuba]], and so are capable of crossing larger than usual bodies of water.<ref name= Rodriguez-Santana/><ref>Hundley, M. H., & Hames, F. (1960). ''Birdlife of the lower Florida Keys''. Florida Audubon Society.</ref> It is thought that Cooper's hawks also avoid the [[Great Plains]] while migrating as well.<ref name="Mueller"/> Like many other raptors, Cooper's hawks favor strong [[Wind direction|northwesterly winds]] during autumn passage.<ref>Haugh, J. R. (1971). ''A STUDY OF HAWK MIGRATION AND WEATHER IN EASTERN NORTH AMERICA''.</ref><ref>Kerlinger, P. (1989). ''Flight Strategies of Migrating Hawks''. University of Chicago Press, Chicago, IL, USA.</ref>

At coastal migration sites like [[Cape May]], first year Cooper's hawks are far more regularly encountered than older individuals, with the juvenile Cooper's accounting for 92.7% of recorded individuals of the species (juveniles of various other raptor species also generally seem to favor coastal over montane migration when it is available).<ref>Clark, W. S. (1985). ''Migration of the Merlin along the coast of New Jersey''. Raptor Res, 19(2/3), 85–93.</ref><ref>Sutton, C., & Sutton, P. (2006). ''Birds and birding at Cape May''. Stackpole Books.</ref> In Cape May, Cooper's hawks are the third most commonly recorded raptor species in passage behind the sharp-shinned hawk and the [[American kestrel]] (''Falco sparverius'') but are far less than numerous in migration or in winter in the nearby [[Delaware Bay]]shore locations of [[New Jersey]] than various other raptor species.<ref name= Sutton>Sutton, C., & Kerlinger, P. (1997). ''The Delaware bayshore of New Jersey: a raptor migration and wintering site of hemispheric significance''. Journal of Raptor Research, 31, 54–58.</ref> In the [[Manzano Mountains]] and [[Goshute Mountains]], juvenile sharp-shinned hawks were roughly twice as numerous as juvenile Cooper's hawks but the number of adults seen passing through of the two species was roughly the same.<ref name= DeLong/> At the [[Hawkwatching|hawkwatch]] in [[Cedar Grove, Wisconsin]], Cooper's hawk was not among the most regular species, being the 6th most frequently most recorded species.<ref>Mueller, H. C., & Berger, D. D. (1961). Weather and fall migration of hawks at Cedar Grove, Wisconsin''. The Wilson Bulletin, 73(2), 171–192.</ref> In central and southwestern [[Idaho]], Cooper's hawk accounted for relatively few of the recorded raptors, i.e. 3.45% of 748 migrating raptors.<ref>Bates, K. K. (2001). ''Monitoring raptors during autumn migration in southwestern and southcentral Idaho''. Bureau of Land Management.</ref> A similarly low volume was observed relative to other bird of prey species in [[Yellowstone National Park]], where Cooper's was only the 9th most frequently observed out of 17 species and averaged only 50 hawks in passage over the course of autumn.<ref>Baril, L. M., Haines, D. B., Walker, L. E., & Smith, D. W. (2018). ''Autumn Raptor Migration in Yellowstone National Park, 2011–2015''. The Canadian Field-Naturalist, 131(4), 303–311.</ref> Nonetheless, Cooper's hawk was second only to sharp-shinned hawk as the most frequently recorded species seen migrating at nine major hawkwatchs throughout the western United States (and 1 in Canada) and, unlike the sharp-shinned, has shown a trend of increase in numbers overall in recent decades, despite some declines in numbers at [[Grand Canyon|Lipan Point]] and [[Bridger Range]].<ref name= Smith2>Smith, J. P., Farmer, C. J., Hoffman, S. W., Kaltenecker, G. S., Woodruff, K. Z., & Sherrington, P. F. (2008). ''Trends in autumn counts of migratory raptors in western North America. State of North America's birds of prey''. Series in Ornithology, 3, 217–251.</ref> Cooper's hawk was the 7th most often recorded raptor at four migration sites along the [[Gulf Coast]], being much more frequently identified in the site at [[Veracruz]], Mexico than the ones in the United States, but showed an annual stability of numbers that many of the more numerous raptors (including sharp-shinned hawks) in passage did not.<ref>Smith, J. P., Farmer, C. J., Hoffman, S. W., Lott, C. A., Goodrich, L. J., Simon, J., Riley, C. & Inzunza, E. R. (2008). ''Trends in autumn counts of migratory raptors around the Gulf of Mexico, 1995–2005''. State of North America's birds of prey. Series in Ornithology, 3, 253–277.</ref> Along the [[Blue Mountain (Pennsylvania)|Kittatinny Ridge]] in Pennsylvania, studied Cooper's hawks that were migrating from further north spent only 12% of the day actually migrating, devoting the remainder of their time to perching and hunting along their passage.<ref>Goodrich, L. J. (2005). ''Migrant raptor habitat use along the Kittatinny Ridge: a critical corridor for eastern flyway birds''. Harrisburg, PA: State Wildlife Grants-Program.</ref> [[Adipose tissue|Fat stores]] were measured to consist of 4–12% of the body mass of migrants, being higher in autumn than in spring, and higher on average in adults over younger hawks and in females over males.<ref>DeLong, J. P., & Hoffman, S. W. (2004). ''Fat stores of migrant Sharp-shinned and Cooper's Hawks in New Mexico''. Journal of Raptor Research, 38(2), 163–168.</ref> Migration speeds appear to be largely similar to those of other raptors, with average speeds of {{convert|33.6|to|88|km/h|mph|abbr=on}}, but one migrating from Colorado was recorded to cover about {{convert|26|km|mi|abbr=on}} per day.<ref name= Goodrich/><ref name= Broun>Broun, M. & Goodwin, B.V. (1943). ''Flight speeds of hawks and crows''. Auk, 60 :487–492.</ref> Typically Cooper's hawk migrate singly but sometimes can be seen in groups of two to five.<ref name= Meng/><ref name= Broun/> [[Flock (birds)|Flocking]] is not typically engaged in by raptors who migrate using powered flight, such as ''Astur'' hawks, ''Accipiter'' hawks, falcons and [[Northern harrier|harrier]]s, but many ''[[Buteo]]'' hawks do form loose flocks.<ref name= Black>Black, R. W., & Borowske, A. (2009). ''The morphology, flight, and flocking behaviour of migrating raptors''. Evolutionary Ecology Research, 11(3), 413–420.</ref> 96.3% of 806 observed Cooper's hawk seen migrating in [[Johnson County, Iowa]] were solitary, although 30 migrating pairs were seen together.<ref name= Black/>

==Diet==

===Hunting methods===
[[File:Cooper's Hawk with kill.jpg|thumb|left|An adult Cooper's hawk with a typical bird kill, appearing to be a male [[house sparrow]].]]
Cooper's hawks are known as bold and aggressive predators.<ref name= Palmer/><ref name= Rosenfield8/> Given their dietary habits, these hawks bore a poor reputation well into the 20th century, with one account describing the species as "noxious", an "avian outlaw" and "a relentless tyrant and murderer of small birds". Another describes the species as "bloodthirsty" and a "villain".<ref name= Bent/><ref>Taylor, W. P., & Shaw, W. T. (1927). ''Mammals and birds of Mount Rainier National Park''. US Government Printing Office.</ref> Early accounts underestimated the opportunistic nature of Cooper's hawks' hunting behavior and provided little insight into the actual effect the hawks have on their prey.<ref name= Palmer/><ref name= Rosenfield8/> The maximum hunting range was estimated at {{convert|5.3|km2|sqmi|abbr=on}} in [[Michigan]] and {{convert|2|km2|sqmi|abbr=on}} in [[Wyoming]].<ref name= Craighead>Craighead, J. J. and F. C. Craighead, Jr. (1956). ''Hawks, owls and wildlife''. Stackpole Co. Harrisburg, PA.</ref> In another Michigan study, most Cooper's hawks were found to be flying {{convert|0.8|to|1.2|km|mi|abbr=on}} from their wooded nests to hunt on agricultural ground.<ref name= Hamerstrom>Hamerstrom Jr, F. N., & Hamerstrom, F. (1951). ''Food of young raptors on the Edwin S. George Reserve''. The Wilson Bulletin, 16–25.</ref> Males in New York usually covered more than {{convert|0.8|km|mi|abbr=on}}, sometimes up to {{convert|3|km|mi|abbr=on}}, during hunting efforts when flying away from the nest area.<ref name= Meng/> Due to scattered prey availability in [[North Florida]], females were nearly nomadic, wandering anywhere where food could be accessed (i.e. [[Poultry farming|chicken farm]]s, [[feedlot]]s, [[bird feeder]]s, etc.), while males were more typically devoted to hunting on their regular home range.<ref name= Millsap/> During hunts, Cooper's hawks rely on agile, twisting flights between bouts of perching and scanning, their flight suddenly picking up speed upon approach to the prey.<ref name=BOW/><ref name= Meng/><ref name= Fischer/> Hunting hawks typically use [[Woodland edge|forest edge]], open [[woodland]] and [[fence]]lines and such while hunting.<ref name= Ferguson-Lees/> In southwestern [[Tennessee]], the preferred hunting habitats in the non-breeding season were forest, then [[woodland edge]], then lastly [[Open terrain|open country]].<ref name= Lake2>Lake, L. A., Buehler, D. A., & Houston, A. E. (2002). ''Cooper's Hawk non-breeding habitat use and home range in southwestern Tennessee''. In Proceedings of the Annual Conference of the Southeastern Association of Fish & Wildlife Agencies (SEAFWA), Tallahassee (Vol. 56, pp. 229–238).</ref> Near [[Stevens Point]] in Wisconsin, males prefer to hunt in quiet woods while females preferred to stay within {{convert|100|m|ft|abbr=on}} of the nest making males a more common sight.<ref name= Murphy/><ref>Rosenfield, R. N., & Bielefeldt, J. (1993). ''Trapping techniques for breeding Cooper's Hawks: two modifications''. Journal of Raptor Research, 27: 170–171.</ref> This differed strongly in Tucson where hawks while hunting mostly in manmade environments such as residential areas, [[regional park]]s, and [[golf course]]s more so than they were prevalent in the environment, though usually where there were large (albeit usually non-native) trees.<ref name= Mannan>Boal, C. W., & Mannan, R. W. (2000). ''Cooper's hawks in urban and exurban areas: a reply''. The Journal of Wildlife Management, 601–604.</ref><ref name= Boggie>Boggie, M. A., & Mannan, R.W. (2014). ''Examining seasonal patterns of space use to gauge how an accipiter responds to urbanization''. Landscape and Urban Planning, 124: 34–42.</ref> Cooper's hawk does attack birds attracted to [[bird feeder]]s with a fair amount of frequency.<ref>Dunn, E. H. (1991). ''Predation at feeders: close encounters of the fatal kind''. Feederwatch News, 4:1–2.</ref><ref>Dunn, E. H., & Tessaglia, D. L. (1994). ''Predation of birds at feeders in winter (Depredación de Aves en Comederos Durante el Invierno)''. Journal of Field Ornithology, 8–16.</ref> However, data from Indiana showed that birds using bird feeders were at no greater risk of attack than those in random transects, and the effect Cooper's can have on feeder birds may be at times exaggerated.<ref name= Roth>Roth, T. C., Vetter, W. E., & Lima, S. L. (2008). ''Spatial ecology of wintering Accipiter Hawks: Home range, habitat use, and the influence of bird feeders''. The Condor, 110(2), 260–268.</ref>
 
If it sees birds when flying, a hunting hawk does not fly directly to them but instead circles around to available trees and bushes often perching for a few moments before launching its attack. If birds become aware of it, the hawk will tend to quickly gain height in hopes of intercepting some prey.<ref name= Brown/> It was found compared to some other North American raptors who are more likely to watch for prey on the ground and/or in the open, that Cooper's hawk had a rather enlarged [[Visual field|binocular field]].<ref>Potier, S., Duriez, O., Cunningham, G. B., Bonhomme, V., O'Rourke, C., Fernández-Juricic, E., & Bonadonna, F. (2018). ''Visual field shape and foraging ecology in diurnal raptors''. Journal of Experimental Biology, 221(14), jeb177295.</ref> During hunts, these hawks may suddenly alight when detecting an available mammal.<ref name= Brown/> Sometimes, Cooper's hawks will engage in [[Pack hunter|tandem hunts]] with one dashing around after the prey while another waits on the other side of a tree trunk or wooded thicket.<ref name= Brown/> Many birds are caught when they inadvertently fly around a tree where a hawk is inconspicuously perched.<ref name= Brown/> Young Cooper's are impetuous about crashing into bushes after prey, sometimes even into thorny cover such as barberries, whereas adults are said to be more "prudent".<ref name= Brown/> They may chase prey into cover or from bush to bush.<ref name= Ferguson-Lees/> The first instance of non-piratical [[Scavenger|scavenging]] on [[carrion]] was recorded when a Cooper's hawk was seen eating at a [[white-tailed deer]] (''Odocoileus virginianus'') carcass.<ref>Davis, W. M. (2000). ''Cooper's Hawk feeding at a deer carcass''. The Mississippi Kite, 12.</ref>

When hunting bats, they can follow all twists and turns, and may succeed in capture in up to 90% of hunts.<ref name= Brown/> Much like goshawk, sometimes Cooper's hawks will capture [[Cottontail rabbit|rabbits]] by pursuing on the ground, half-running, half-flying.<ref name= Brown/> Other on-foot hunting efforts, especially when chasing [[New World quail|quail]], have been detected as well.<ref name=BOW/><ref name= Rosenfield8/> When hunting [[House sparrow|sparrows]], Cooper's hawks may make multiple passes on a bush before success and the efforts can take up to 45 minutes.<ref name= Palmer/> During hunts of [[feral pigeon]]s (''Columba livia)'' in urban areas, Cooper's hawks have been seen to engage in open air [[Bird flight|stoop]]s to capture the prey.<ref name= Mead>Mead, R. A. (1963). ''Cooper's Hawk attacks pigeon by stooping''. Condor, 65:167.</ref><ref name= Clark2>Clark, R. J. (1977). ''Cooper's Hawk hunting in the city''. Auk, 94:142–143.</ref> An unusual [[Harrier (bird)|harrier]]-like flight was seen in be engaged in by a Cooper's hawk before an attack on [[Grebe|aquatic prey]] in a [[marsh]].<ref name= Palmer/> Most prey is killed by repeatedly kneading the talons, with the kneading sometimes going on even after death, although in some cases birds are plucked while still alive.<ref name= Palmer/><ref name= Jones>Jones, S. (1979). ''Habitat management series for unique or endangered species''. Report No. 17, the Accipiters. USDI-BLM Tech. Note 335.</ref> Despite its [[Gracility|gracile]] appearance, Cooper's hawk is extremely powerful for its size and presumably able to capture larger prey relative to its size than other raptors such as falcons and ''Buteos'' (including [[red-tailed hawk]]s (''Buteo jamaicensis'')) due to its unusually high-speed foot [[velocity]] and resulting impact during prey captures.<ref name= Goslow>Goslow, G. E. (1971). ''The attack and strike of some North American raptors''. The Auk, 88(4), 815–827.</ref><ref>Sustaita, D. (2008). ''Musculoskeletal underpinnings to differences in killing behavior between North American accipiters (Falconiformes: Accipitridae) and falcons (Falconidae)''. Journal of Morphology, 269(3), 283–301.</ref> At times, after capture, Cooper's hawk have been seen to hold still living prey underwater, presumably trying to [[drown]] it.<ref name= Palmer/><ref name= Forbush>Forbush, E. H. (1927). ''Birds of Massachusetts and other New England states. Part II''. Land birds from Bobwhites to Grackles. Mass. Dept.</ref><ref>Gerig, J. (1979). ''Death by drowning-one Cooper's hawk approach''. Am. Birds, 33: 836.</ref> Subsequent to the preys' demise, they may eat the victim head first, followed by the [[Organ (anatomy)|viscera]], with the meat eaten lastly.<ref name= Meng/> Like other raptors who most regularly take birds, Cooper's hawk was profiled in a study as an "attacker" rather than a "searcher" (i.e. [[mammal]]-hunters such as ''Buteos''). "Attackers" such as ''Accipiter'' and ''Astur'' hawks and large [[falcon]]s usually had lower average hunting success rates, which averaged among the attacker species at 27%, due to the difficulty of capturing the prey.<ref>Toland, B. (1986). ''Hunting success of some Missouri raptors''. The Wilson Bulletin, 116–125.</ref> 33% of 45 observed hunts in a study in [[Missouri]] were successful.<ref name= Toland/> In [[Terre Haute, Indiana]], about 23% of attacks by male Cooper's hawks and 20% by females were successful and were far more prone to being carried out in relatively open areas than those of nearby sharp-shinned hawk.<ref name= Roth2>Roth II, T. C., & Lima, S. L. (2006). ''Predatory behavior and diet of wintering male Cooper's Hawks in a rural habitat''. Journal of Raptor Research, 40(4), 287–290.</ref> Post-fledgling [[Pack hunter|parties]] of hawks in Wisconsin were seen to hunt in sibling groups of 2–4, mainly pursuing [[Eastern chipmunk|chipmunks]], and were observed to succeed in 56% of 18 hunting attempts.<ref name= Nicewander>Nicewander, J., & Rosenfield, R. N. (2006). ''Behavior of a brood of post-fledging Cooper's Hawks: non-independence of sibling movements''. Passenger Pigeon, 68, 321–343.</ref> During the first six weeks after the young hatch, in New York, it was estimated that a male Cooper's hawk would need to procure about 66 prey items over the period.<ref name= Meng2>Meng, H. (1959). ''Food habits of nesting Cooper's hawks and goshawks in New York and Pennsylvania''. The Wilson Bulletin, 71(2), 169–174.</ref> In these first six weeks in California, it was thought a minimum of {{convert|62|g|oz|abbr=on}} would be required per nestling per day.<ref name= Fitch2>Fitch, H. S., Glading, B., & House, V. (1946). ''Observations on Cooper Hawk nesting and predation''. California Fish and Game, 32(3), 144–154.</ref>

===Prey spectrum===
[[File:Coopers Hawk (6060494308).jpg|thumb|A Cooper's hawk with a [[common grackle]] as its prey]]

Cooper's hawk may consume well over 300 prey species from across the range. This predator is known to consume [[vertebrate]] prey almost exclusively.<ref name= Ferguson-Lees/> Often smallish or medium-sized birds are the preferred food, but also many small [[mammal]]s and, in more arid vicinities, lizards are regularly taken. Infrequently, frogs may be eaten, as will (rarely) insects and fish in nearly dry watercourse.<ref name= Ferguson-Lees/><ref>Smith, A. P. (1915). ''Birds of the Boston Mountains, Arkansas''. The Condor, 17(1), 41–57.</ref> Birds in general form about 50–85% of diet.<ref name= Ferguson-Lees/> One estimate is that globally birds form about 71.1% of the diet, 17.9% mammals, 8.9% reptiles and 2.1% other prey.<ref name= Jones/> Cooper's hawks generally prefers birds that inhabit the ground or [[shrub]] level within the local habitats.<ref name=BOW/> One estimate claims that most prey of Cooper's hawks weighs from {{convert|15|to|166|g|oz|abbr=on}}, with male and female averages of {{convert|37.6|and|50.7|g|oz|abbr=on}}.<ref name= Storer>Storer, R. W. (1966). ''Sexual dimorphism and food habits in three North American accipiters''. The Auk, 83(3), 423–436.</ref> Another estimate was from {{convert|30|to|130|g|oz|abbr=on}} for typical prey sizes, or about 5–37% the weight of males and 8–22% the weight of females, respectively.<ref name=BOW/><ref name= Rosenfield8/> However, subsequent studies, such as those in [[Indiana]], found prey weighing up to {{convert|360|g|oz|abbr=on}} (such as adult [[Rock dove|pigeons]]) can be quite common in the diet of Cooper's hawks. Mean prey weights were roughly {{convert|112.6|g|oz|abbr=on}}.<ref name= Roth3>Roth II, T. C., & Lima, S. L. (2003). ''Hunting behavior and diet of Cooper's hawks: an urban view of the small-bird-in-winter paradigm''. The Condor, 105(3), 474–483.</ref> In Oregon, the mean prey sizes of Cooper's hawk was {{convert|135.5|g|oz|abbr=on}}, with larger prey was taken than in greater proportion than their occurrence in the ecosystem (indicating that they locally search out relatively large prey).<ref name= Reynolds3>Reynolds, R. T., & Meslow, E. C. (1984). ''Partitioning of food and niche characteristics of coexisting Accipiter during breeding''. The Auk, 101(4), 761–779.</ref> In Missouri, mean prey sizes were {{convert|112|g|oz|abbr=on}}, averaging between {{convert|83.5|and|316.5|g|oz|abbr=on}} amongst the main prey classes. Prey delivered by males averaged an estimated {{convert|65.9|g|oz|abbr=on}}, while the average estimated size of prey delivered by females was {{convert|227.7|g|oz|abbr=on}}. Overall, in Missouri, prey body masses were estimated to range from {{convert|15|to|600|g|oz|abbr=on}}.<ref name= Toland/> One study unusually found no strong dimorphism in the foods selected by males and females.<ref name= Kennedy2>Kennedy, P. L., & Johnson, D. R. (1986). ''Prey-size selection in nesting male and female Cooper's Hawks''. The Wilson Bulletin, 110–115.</ref>

===Birds===

====Predation rates and passerines====
[[File:Accipiter cooperii DM3.jpg|thumb|An adult Cooper's hawk that has caught a [[common starling]], one of the most widely taken prey for this species.]]
Birds are by far the leading prey for Cooper's hawks in most areas. A wide diversity of birds, considerably over 250 species, are known to be taken, constituting more than three-quarters of known prey species for these hawks.<ref name=BOW/><ref name= Rosenfield8/> A Cooper's hawk is estimated to kill an average of two birds a day, or 700 birds a year.<ref>Walsberg, G. E. (1994). ''The use of wild birds in research''. Condor, 96: 1119–1120.</ref> Although prior data mostly reflected the taking of adult birds, a study in Wisconsin revealed that Cooper's hawks may largely take young of the year, mostly fledglings but also not infrequently nestlings, during the breeding season. 74% of ageable bird prey in this study were young of the year.<ref name= Bielefeldt>Bielefeldt, J., Rosenfield, R. N., & Papp, J. M. (1992). ''Unfounded assumptions about diet of the Cooper's Hawk''. The Condor, 94(2), 427–436.</ref> Similarly, in Michigan during summer, immature birds were more than 2.5 times more often delivered to Cooper's hawk nests than adult birds.<ref name= Hamerstrom/> In one case, a Cooper's hawk was seen to fly away with an entire occupied nest of [[American goldfinch]]es (''Spinus tristis'').<ref>Linduska, J. P. (1943). ''Cooper's Hawk carrying a nest of young Goldfinches''. The Auk, 60(4), 597–597.</ref> One study determined that birds that nest in the [[canopy (biology)|canopy]] level tended to nest fairly close to this hawk but those with mid-level, shrub level and ground level nests nested farther away, indicating that non-canopy-nesting birds are generally taken during the breeding season.<ref>Duncan, W. J., & Bednekoff, P. A. (2008). ''Nesting with an enemy: The abundance and distribution of preferred and secondary prey near nesting Cooper's hawks, Accipiter cooperii''. Ethology Ecology & Evolution, 20(1), 51–59.</ref> Key to prey selection for Cooper's hawk is the availability and abundance of birds in a given region.<ref name=  Millsap/><ref name= Kennedy2/> Therefore, the extremely numerous [[American robin]] (''Turdus migratorius'') appears to be the most widely reported prey species. Robins were the leading prey species in northwestern [[Oregon]], at 19.6% of 281 prey items, [[Lopez Island]], [[Washington (state)|Washington]], 23.4% of 107 prey items, in [[Victoria, British Columbia]], at 34.6% of 2896 prey items and prominent but ranked second also in California ([[Berkeley, California|Berkeley]] and [[Albany, California|Albany]]) food studies, 24.5% of 1057 prey items.<ref name= Reynolds3/><ref name= Kennedy2/><ref name= Cava>Cava, J. A., Stewart, A. C., & Rosenfield, R. N. (2012). ''Introduced species dominate the diet of breeding urban Cooper's Hawks in British Columbia''. The Wilson Journal of Ornithology, 124(4), 775–782.</ref><ref name= Haiman>{{cite web | last=Haiman | first=Aaron N. K. | url=https://nature.berkeley.edu/classes/es196/projects/2006final/haiman.pdf | title=Prey Selection of Cooper's Hawks (''Accipiter cooperii'') Nesting in Urban Areas of Berkeley and Albany, California | publisher=Environmental Sciences Group, University of California, Berkeley | date=May 8, 2006| access-date=June 13, 2020}}</ref> The robin is regularly hunted in all seasons due to its commonality in [[exurb]]an regions, with both adults, at estimated averages of {{convert|79|to|81.2|g|oz|abbr=on}} when taken, and young being relatively easy for them to access.<ref name= Toland/><ref name= Reynolds3/><ref>Stewart, A. C. (2003). ''Observations of Nest Predation by Cooper's hawks on Vancouver Island, British Columbia''. British Columbia Birds, 13.</ref> Beyond the common robin, nearly all [[Thrush (bird)|thrushes]] in North America (excluding one [[Gray-cheeked thrush|species]] whose breeding range is largely north of Cooper's range and one [[Bicknell's thrush|rare, little-studied species]]) are opportunistically hunted by Cooper's hawks.<ref name= Cartron/><ref name= Millsap/><ref name= Reynolds3/><ref name= Sherrod>Sherrod, S. K. (1978). ''Diets of North American Falconiformes''. Raptor Res, 12(3/4), 49–121.</ref><ref name= Reynolds4>Reynolds, R. T. (1978). ''Food and habitat partitioning in two groups of coexisting Accipiter''. Thesis. Dept of Fish and Wildlife.</ref><ref>Bowen, R. V. (1997). ''Townsend's Solitaire (Myadestes townsendi)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref><ref>Heckscher, C. M., L. R. Bevier, A. F. Poole, W. Moskoff, P. Pyle, and M. A. Patten (2017). ''Veery (Catharus fuscescens)'', version 3.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> The closest rival to the robin in being most widely taken as prey for Cooper's hawks may be the [[common starling]] (''Sturnus vulgaris''), a [[Invasive species|non-native bird]] in North America with mean weights when taken of {{convert|79|to|82|g|oz|abbr=on}}. The starling was the main food for these hawks in [[Ithaca, New York]], at 28.2% of 857 prey items, and [[Terre Haute, Indiana]], at 56.5% of 57 prey items, and taken in large but somewhat secondary numbers in Missouri, [[Michigan]], and Victoria, British Columbia.<ref name= Toland/><ref name= Hamerstrom/><ref name= Meng2/><ref name= Cava/><ref name= Roth3/> In the urban environment of Terre Haute, it was found that starlings were taken in almost the same proportion as starlings were of all birds observed by researchers (i.e. they were 60% of 2146 individual birds seen).<ref name= Roth3/>

Somewhat over 60% of the bird species known in Cooper's hawks' prey spectrum are [[passerine]]s (including thrushes and starlings). Other medium-sized to largish-bodied families of passerines tend to be most often selected.<ref name= Rosenfield8/> In many circumstances, Cooper's hawks will hunt [[corvid]]s, large, intelligent and social passerines, with the smallish [[jay]]s being particularly popular.<ref name= Palmer/><ref name=BOW/> In Missouri, the most often selected prey (12.7% of 259 prey items) was the {{convert|89|g|oz|abbr=on}} [[blue jay]] (''Cyanocitta cristata''), which also important in northern Florida, i.e. 12.27% of 1100 prey items.<ref name= Toland/><ref name= Millsap/> [[Steller's jay]]s (''Cyanocitta stelleri''), at {{convert|107|g|oz|abbr=on}} a larger western cousin of the blue jay, are also regularly selected in various studies, such as all studied areas of [[Oregon]] and [[New Mexico]], where it was the second most regularly selected of prey species at 11.7% of 316 prey items.<ref name= Reynolds3/><ref name= Kennedy3>Kennedy, P. L. (1992). ''Reproductive strategies of Northern Goshawks and Cooper's Hawks in north-central New Mexico''. Phd, University of Utah.</ref> [[California scrub jay]]s (''Aphelocoma californica'') are regular supplemental prey in [[northern California]] studies as well.<ref name="Haiman" /> Blue jays and other related species are among the most diligent [[Mobbing (animal behavior)|mobbing]] birds in response to the presence of a Cooper's hawk although sometimes may let out an alarm call or even imitate a Cooper's calls merely to frighten other birds from a desired food source.<ref>Hailman, J. P. (2009). ''Context of blue jay (Cyanocitta cristata) mimicking Cooper's Hawk (Accipiter cooperii) cackle''. Florida Field Naturalist, 37(3), 94–94.</ref><ref>Hailman, J. P., McGowan, K. J., & Woolfenden, G. E. (1994). ''Role of helpers in the sentinel behaviour of the Florida scrub jay (Aphelocoma c. coerulescens)''. Ethology, 97(1‐2), 119–140.</ref> It was hypothesized that Steller's jays may be able to effectively confuse a Cooper's hawk by engaging in a chorus of calls at close range.<ref>Ficken, M. S. (1989). ''Are Mobbing Calls of Steller's Jays a" Confusion Chorus"?(¿ Son las Llamadas de Tumultos en Cyanocitta stelleri un" Coro de Confusión"?)''. Journal of Field Ornithology, 52–55.</ref> In [[Arizona]], [[Mexican jay]]s (''Aphelocoma ultramarina'') are known to play a key role in [[Northern flicker|flicker]] ecology by watching out for Cooper's hawks.<ref name= Jones2>Jones, Z. F., & Bock, C. E. (2003). ''Relationships between Mexican Jays (Aphelocoma ultramarina) and Northern Flickers (Colaptes auratus) in an Arizona oak savanna''. The Auk, 120(2), 429–432.</ref> Numerous other corvids may be hunted, including most overlapping jays, as well as the [[Clark's nutcracker]] (''Nucifraga columbiana''), [[black-billed magpie]] (''Pica hudsonia''), possibly [[yellow-billed magpie]] (''Pica nuttalli'') and a few species of [[crow]].<ref name= Cartron/><ref name= Reynolds3/><ref>Cowan, E. M. (2005). ''Reproductive success, territory size, and predation pressuresof the Florida scrub-jay (Aphelocoma coerulescens) at Savannas Preserve State Park''. Florida Atlantic University.</ref><ref>Balda, R. P., & Bateman, G. C. (1971). ''Flocking and annual cycle of the pinon jay, Gymnorhinus cyanocephalus''. Condor, 287–302.</ref><ref>Koenig, W. D. and M. D. Reynolds (2009). ''Yellow-billed Magpie (Pica nuttalli)'', version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> One black-billed magpie was caught and killed by a Cooper's hawk when attempting to mob the hawk.<ref>Holroyd, G. L. (2002). ''Mobbing Black-billed Magpie, Pica hudsonia killed by Cooper's Hawk, Accipiter cooperii''. Canadian Field-Naturalist, 116: 137–138.</ref> Incidents of predation have been witnessed on both young and adult [[American crow]]s (''Corvus brachyrhynchos''). These hawks are also a potential predator of [[fish crow]] (''Corvus ossifragus'').<ref name= Mukherjee>Mukherjee, S., & Heithaus, M. R. (2013). ''Dangerous prey and daring predators: a review''. Biological Reviews, 88(3), 550–563.</ref><ref name= McNicholl>McNicholl, M. K. (2012). ''Cooper's Hawk predation on Northwestern Crow''. Journal of the British Columbia Field Ornithologists, 22.</ref><ref>McGowan, K. J. (2001). ''Demographic and behavioral comparisons of suburban and rural American Crows''. In Avian ecology and conservation in an urbanizing world (pp. 365–381). Springer, Boston, MA.</ref><ref>Reese, J. G. (2015). ''Fish Crows (Corvus ossifragus) Utilize Unusual Nesting Location and Habitat''. Maryland Birdlife, 64(1), 42–50.</ref> However, crows are potentially dangerous prey to Cooper's hawks. Adult American crows are about the same size as a female Cooper's hawk and can potentially cause considerable damage to a lone raptor during group [[Mobbing (animal behavior)|mobbing]], being capable of inflicting damage with both their feet and bill.<ref name= Richardson>Richardson, F. (1957). ''Cooper's hawk knocked down by crows''. The Murrelet, 37.</ref> In at least one case, a murder of American crows was observed to drive a Cooper's hawk to the ground and possibly seriously injure it, although the fate of the hawk was not certain.<ref name= Richardson/> Cases of missing toes on Cooper's hawks are thought to have possibly come from failed predation of crows.<ref name= Mukherjee/> At least a dozen species of [[icterid]] are known to be hunted by Cooper's hawks as well. Common, widespread icterids such as [[red-winged blackbird]]s (''Agelaius phoeniceus'') and [[common grackle]]s (''Quiscalus quiscula'') are fairly frequent prey for these hawks.<ref name= Toland/><ref name= Meng2/><ref name= Hamerstrom/> Cooper's hawks nesting near red-winged blackbird colonies may at times live almost entirely off of female blackbirds.<ref>Westneat, D. F. (1992). ''Nesting synchrony by female red‐winged blackbirds: effects on predation and breeding success''. Ecology, 73(6), 2284–2294.</ref> In the [[Black Hills]], although prey species were seldom identified, evidence showed that most regularly selected prey were assorted icterids.<ref name= Stephens>Stephens, R. M., & Anderson, S. H. (2002). ''Conservation assessment for Cooper's Hawk and the Sharp-shinned Hawk in the Black Hills National Forest, South Dakota and Wyoming''. USDA Forest Service, Rocky Mountain Region, Custer, ND.</ref> Even [[meadowlark]]s, such as the {{convert|93|g|oz|abbr=on}} [[eastern meadowlark]] (''Sturnella magna'') which was the third most often selected prey in Ithaca, New York, and [[bobolink]]s (''Dolichonyx oryzivorus'') are taken despite their preference for [[grassland]]s well outside the typical habitats of Cooper's hawks.<ref name= Meng2/><ref name= Reynolds3/><ref name= Sherrod/>

[[File:Cooper's Hawk Eating a Finch.jpg|thumb|left|Eating a finch in a backyard with feeders]]

Other passerines families (i.e. outside thrushes, corvids and icterids) tend to not be as large-bodied and, although by no means neglected, are seldom equal in overall dietary importance ([[biomass]]). About 15 species of [[tyrant flycatcher]], several species each of [[vireo]], [[Swallow (bird)|swallows]], [[Tit (bird)|tits]], [[nuthatch]]es, [[wren]]s, [[mimid]]s, about a dozen species of [[finch]], [[Cardinalidae|cardinalids]] and a huge diversity of [[American sparrow]]s and [[New World warbler]]s (nearly 30 species each) are known to be taken by Cooper's hawks.<ref name=BOW/><ref name= Millsap/><ref name= Storer/><ref name= Sherrod/> A lower diversity are taken of [[Loggerhead shrike|shrikes]], [[larks]], [[Verdin|penduline tits]], [[American bushtit|aegithalids]], [[Brown creeper|treecreepers]], [[American dipper|dippers]], [[Phainopepla|silky-flycatcher]]s and [[Calcariidae|longspurs]].<ref name=BOW/><ref name= Millsap/><ref name= Storer/><ref name= Sherrod/> The more numerous native passerines, such as [[northern cardinal]]s (''Cardinalis cardinalis'') and [[northern mockingbird]]s (''Mimus polyglottos''), have good reason to fear these hawks as they are widely and regularly taken as are even common birds of less than half their size (around {{convert|20|g|oz|abbr=on}}), such as [[song sparrow]]s (''Melospiza melodia''), [[dark-eyed junco]]s (''Junco hiemalis'') and [[house finch]]es (''Haemorhous mexicanus'').<ref name= Storer/><ref name= Millsap/><ref name= Cava/><ref name= Reynolds3/><ref>Zanette, L., Smith, J. N., Oort, H. V., & Clinchy, M. (2003). ''Synergistic effects of food and predators on annual reproductive success in song sparrows''. Proceedings of the Royal Society of London. Series B: Biological Sciences, 270(1517), 799–803.</ref><ref>Duncan, W. J., & Bednekoff, P. A. (2006). ''Singing in the shade: song and song posts of northern cardinals near nesting Cooper's hawks''. Canadian journal of zoology, 84(6), 916–919.</ref> During harsh late winter weather in Wisconsin, Cooper's hawks were recorded to eke out an existence living largely off of [[pine siskin]]s (''Spinus pinus'').<ref name= Snowstorm>Rosenfield, R. N. (2019). ''Riding the storm out: select demographics of a breeding population of Cooper's Hawks (Accipiter cooperii) following a severe spring snowstorm''. Raptor Journal 13: In press.</ref> In modern terms, certainly the most commonly taken small bird would be the non-native, {{convert|29|g|oz|abbr=on}} [[house sparrow]] (''Passer domesticus''). Although not known to be taken profusely in all studied urban locales, house sparrows were the leading prey in a study from [[Michigan]], were nearly a third of observed delivered prey at nests in [[Victoria, British Columbia]] (although were outnumbered by robins in prey remains) and reportedly were the leading prey in [[Milwaukee]] and in [[Grand Forks, North Dakota]].<ref name=BOW/><ref name= Cava/><ref name= Hamerstrom/> [[Tyrant flycatcher|Flycatchers]] are not hugely significant in Cooper's hawk's foods, but the local effect of the hawks on populations can be considerable. For example, [[willow flycatcher]]s (''Empidonax traillii'') in California suffered a 76% rate of nest predation, among which Cooper's hawks were a considerable contributor, and [[American dusky flycatcher|dusky flycatcher]]s (''Empidonax oberholseri'') experienced a rate of 96% predation elsewhere in California, with 25% attributable to Cooper's.<ref>Cain III, J. W., Morrison, M. L., & Bombay, H. L. (2003). ''Predator activity and nest success of willow flycatchers and yellow warblers''. The Journal of wildlife management, 600–610.</ref><ref>Liebezeit, J. R., & George, T. L. (2002). ''Nest predators, nest-site selection, and nesting success of the Dusky Flycatcher in a managed ponderosa pine forest''. The Condor, 104(3), 507–517.</ref> Similar determent to the local nesting attempts of other small passerines such as warblers has also been reported.<ref>Schaef, K. M., & Mumme, R. L. (2012). ''Predator vocalizations alter parental return time at nests of the Hooded Warbler''. The Condor, 114(4), 840–845.</ref><ref name= Stake>Stake, M. M., Faaborg, J., & Thompson, F. R. (2004). ''Video identification of predators at golden-cheeked warbler nests''. Journal of Field Ornithology, 75(4), 337–344.</ref> [[Chickadee]]s seem to regard Cooper's hawks as a moderate threat based on their anti-predator response, with smaller raptors (which are presumably more dangerous) such as sharp-shinned hawks and small owls evoking a rather more aggressive response by chickadees.<ref>Templeton, C. N., Greene, E., & Davis, K. (2005). ''Allometry of alarm calls: black-capped chickadees encode information about predator size''. Science, 308(5730), 1934–1937.</ref><ref>Soard, C. M., & Ritchison, G. (2009). ''<nowiki />'Chick-a-dee'calls of Carolina chickadees convey information about degree of threat posed by avian predators''. Animal Behaviour, 78(6), 1447–1453.</ref> While usually the smallest avian prey selected by Cooper's hawks are various warblers (presumably taken mainly by male hawks), down to the size of the {{convert|7|g|oz|abbr=on}} [[Wilson's warbler]] (''Cardellina pusilla''), even smaller passerines are known to be hunted.<ref name= Reynolds3/><ref name= CRC>{{cite book |title=''CRC Handbook of Avian Body Masses'' |edition=2nd |editor-first=John B. Jr. |editor-last=Dunning |publisher=CRC Press |year=2008 |isbn=978-1-4200-6444-5}}</ref> The smallest known avian prey species have included the {{convert|6.8|g|oz|abbr=on}} [[verdin]] (''Auriparus flaviceps''), the {{convert|6.3|g|oz|abbr=on}} [[ruby-crowned kinglet]] (''Corthylio calendula'') and the {{convert|5.3|g|oz|abbr=on}} [[American bushtit|bushtit]] (''Psaltriparus minimus'').<ref name= Haiman/><ref name= CRC/><ref name= Boal3>Boal, C. W., & Mannan, R. W. (1996). ''Nest-site selection of Cooper's hawks in urban environments and the effects of trichomoniasis on reproductive success''. Arizona Game and Fish Department.</ref><ref>Webster, M. D. (1999). ''Verdin (Auriparus flaviceps)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> Even smaller birds, the [[hummingbird]]s, are essentially immune to Cooper's hawks (due to their own extreme agility) and were seen to incidentally benefit from nesting close to the hawks in California, due to a low risk of predators approaching while the hawks are present.<ref>Greeney, H. F. & Wethington, S.M. (2009). ''Proximity to active accipiter nests reduces nest predation of Black-chinned Hummingbirds''. Wilson Journal of Ornithology, 121:809–812.</ref><ref>Greeney, H. F., Meneses, M. R., Hamilton, C. E., Lichter-Marck, E., Mannan, R. W., Snyder, N., Wethington, S.M. & Dyer, L. A. (2015). ''Trait-mediated trophic cascade creates enemy-free space for nesting hummingbirds''. Science advances, 1(8), e1500310.</ref>

====Columbids and woodpeckers====
[[File:Cooper's hawk eating in winter (52562).webm|thumb|right|Cooper's hawk eating a bird, likely a [[mourning dove]], in New York City]]
Outside of passerines, almost certainly the most important avian prey type is the [[Columbidae|pigeon and dove]] family. Especially for those living in urban areas, Cooper's hawks have seemed to take to living heavily off of [[dove]]s, particularly the abundant and widely found [[mourning dove]] (''Zenaida macroura''), at {{convert|119|g|oz|abbr=on}}. Mourning doves appear to be hunted regularly in almost any part of the two species' mutual range.<ref name=BOW/><ref name= CRC/> In [[Tucson]], recent data shows that Cooper's hawks are living almost exclusively on doves. Among 151 prey items there, mourning doves were 20.5% by number and 27.5% of the biomass, [[Inca dove]]s (''Columbina inca'') were 18.5% by number and 12.2% of the biomass and [[white-winged dove]] (''Zenaida asiatica'') 17.2% by number and 27.1% of the biomass.<ref name= Estes/> In [[Terre Haute, Indiana]], mourning doves and [[rock dove]]s were 14% and 21% of the diet, respectively.<ref name= Roth3/> In northern California, mourning doves were the main prey species, making up 25.6% of 1057 prey items.<ref name= Haiman/> There is even evidence that [[bluebird]]s have perceived the change in preference of Cooper's hawks to more profitable prey such as doves in developed areas and show less inhibition to the hawk's presence.<ref>Malone, K. M., Powell, A. C., Hua, F., & Sieving, K. E. (2017). ''Bluebirds perceive prey switching by Cooper's hawks across an urban gradient and adjust reproductive effort''. Ecoscience, 24(1–2), 21–31.</ref> In the more rural [[north Florida]], again the mourning dove leads the prey selection, accounting for 16.5% of 1100 prey items.<ref name= Millsap/>

[[File:Cooper&#039;s Hawk with pigeon.jpg|thumb|left|An immature Cooper's hawk who has caught a [[Rock dove|pigeon]]]]
Another popular prey family is the [[woodpecker]]s. A rather numerous and widely distributed species, the {{convert|132|g|oz|abbr=on}} [[northern flicker]] (''Colaptes auratus''), is a particular dietary staple of Cooper's hawks, being about the third most widely reported prey species.<ref name=BOW/><ref name= Cartron/><ref name= Rosenfield8/><ref name= Meng2/> The flicker was the main prey in northern [[New Mexico]], at 22.5% of 316 prey items, and in southern Wisconsin, at 22% of 77 prey items.<ref name= Kennedy3/><ref name= Errington>Errington, P. L. (1933). ''Food habits of southern Wisconsin raptors. Part II. Hawks''. The Condor, 35(1), 19–29.</ref> Flickers are common prey elsewhere as well, such as in [[Ithaca, New York]].<ref name= Meng2/> Medium-sized woodpeckers, such as [[red-headed woodpecker]]s (''Melanerpes erythrocephalus'') and [[red-bellied woodpecker]]s (''Melanerpes carolinus'') were important secondary prey in different parts of the range. In [[South Carolina]], it was found that 15% of the red-headed woodpeckers in a study population were killed by hawks.<ref name= Toland/><ref name= Millsap/><ref name= Errington/><ref>Vukovich, M., & Kilgo, J. C. (2009). ''Notes on breeding sharp-shinned hawks and Cooper's hawks in Barnwell County, South Carolina''. Southeastern Naturalist, 8(3), 547–552.</ref> All told, about 20 species (almost all in North America but for a couple poorly studied species) of woodpecker are known to be taken, ranging from the smallest, the {{convert|25.6|g|oz|abbr=on}} [[downy woodpecker]] (''Dryobates pubescens''), to the largest, the {{convert|287|g|oz|abbr=on}} [[pileated woodpecker]] (''Dryocopus pileatus'').<ref name= Cartron/><ref name= Sherrod/><ref name= Reynolds3/><ref name= CRC/><ref name= Boal3/> The response of woodpeckers to a sighted Cooper's hawks varies, with evidence showing that downy woodpecker and flickers would behave more boldly and themselves may scold the hawk if part of a [[Mixed-species foraging flock|mixed flock]] but, if alone, the woodpecker will typically try to flee.<ref name= Jones2/><ref>Sullivan, K. (1985). ''Selective alarm calling by downy woodpeckers in mixed-species flocks''. The Auk, 184–187.</ref> Despite the regularity of predation of woodpeckers that are in the open, a study in British Columbia shows indicated Cooper's hawks seldom prey upon woodpecker nests, perhaps due to being unable to access their secluded, smallish nest holes, with the study showing that the most regular predators of such nests were various mammals (from [[North American deermouse|deermice]] to [[American black bear|bears]]).<ref>Walters, E. L., & Miller, E. H. (2001). ''Predation on nesting woodpeckers in British Columbia''. Canadian Field-Naturalist, 115(3), 413–419.</ref>

====Galliforms====
Certainly the most controversial aspect of Cooper's hawks are their predations upon [[Galliformes|galliforms]]. By far the most regularly selected types are [[New World quail]]s. Coveys of quails that attempt to evade predators by running into thick vegetation (which can allow them to successfully escape many predators) often find that Cooper's hawks are undeterred by this, as the hawks may chase them either on the wing or on foot into thickets.<ref>Williams, C. K., Lutz, R. S., & Applegate, R. D. (2003). ''Optimal group size and northern bobwhite coveys''. Animal Behaviour, 66(2), 377–387.</ref> However, one [[Ruffed grouse|grouse]] was seen to successfully evade a hunting Cooper's hawk by diving belly first into about a foot of snow.<ref>Prawdzik, T. R. (1963). ''Ruffed grouse escaping a Cooper's hawk''. The Journal of Wildlife Management, 639–642.</ref> Cooper's hawks are often regarded as perhaps the most regular natural predator of [[northern bobwhite]]s (''Colinus virginianus''). Indeed, the rate of predation by Cooper's does appear to exceed that committed by other species of hawk as well as that by large owls.<ref>Stoddard, H. (1931). ''The bobwhite quail—its life and management''. Charles Scribner's Sons, New York City, USA.</ref><ref>Cox, S. A., Peoples, A. D., DeMaso, S. J., Lusk, J. J., & Guthery, F. S. (2004). ''Survival and cause‐specific mortality of northern bobwhites in western Oklahoma''. The Journal of Wildlife Management, 68(3), 663–671.</ref><ref>Cox, S. A., Guthery, F. S., Lusk, J. J., Peoples, A. D., DeMaso, S. J., & Sams, M. (2005). ''Reproduction by northern bobwhites in western Oklahoma''. The Journal of wildlife management, 69(1), 133–139.</ref><ref name= Terhune>Terhune, T. M., Sisson, D. C., Palmer, W. E., Stribling, H. L., & Carroll, J. P. (2008). ''Raptor predation of Northern Bobwhite nests''. Journal of Raptor Research, 42(2), 148–150.</ref><ref name= Millsap3>Millsap, B. A., Breen, T., & Silvmania, L. (2000). ''Preliminary findings on the foraging ecology of a northern bobwhite predator in North Florida: the Cooper's hawk (Accipiter cooperii)''. In National Quail Symposium Proceedings (Vol. 4, No. 1, p. 24).</ref> For instance, during winter in Wisconsin, Cooper's hawks were thought to kill 3.4–12.5% of the local bobwhite population.<ref>Errington, P. L., & Errington, P. E. (1933). ''The nesting and the life equation of the Wisconsin bob-white''. The Wilson Bulletin, 122–132.</ref> However, the bobwhite appears to be a secondary prey species in all known studies and there is no evidence that Cooper's hawk predation alone can deplete bobwhite populations, unlike causes directly contributable to man such as [[Overexploitation|overhunting]] and [[habitat destruction]].<ref name= Toland/><ref name= Millsap/><ref name= Terhune/><ref name= Millsap3/> In Washington state, female Cooper's hawks took many [[California quail]]s (''Callipepla californica''), which were estimated to constitute 47% of the prey selected by female hawks, but there was far too little impact overall to affect the quail's overall population.<ref name= Kennedy2/> In the rural areas outside of [[Tucson]], [[Gambel's quail]] (''Callipepla gambelii'') were found to be the most regularly selected prey species, at 15.2% of 79 prey items.<ref name= Boal/> A study of pellets in northwestern Mexico to determine if the local Cooper's hawks were regularly taking [[Montezuma quail]] (''Cyrtonyx montezumae''), finding that only one pellet consisted entirely of quail, the other pellets showing that hawks were mainly taking other prey, mostly doves.<ref>Ibarra-Zimbrón, S., Álvarez, G., Mendoza-Martínez, G., Zaragoza-Hernández, C., Tarango-Arámbula, L. A., & Clemente-Sánchez, F. (2001). ''Morfología y dieta del gavilán de Cooper (Accipiter cooperii) en la región noroeste del Estado de México''. Revista Chapingo Serie Ciencias Forestales y del Ambiente, 6(1), 63–68.</ref> Most regularly found galliforms in North America (including well-established exotics such as [[chukar partridge|chukars]] (''Alectoris chukar'') and [[common pheasant]]s (''Phasianus colchicus'')) are known to fall prey occasionally to Cooper's hawks.<ref name= Errington/><ref>Christensen, G. C. (1996). ''Chukar (Alectoris chukar)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> These include assorted native [[grouse]], including even the [[grassland]]-dwelling species (but excluding the more northerly distributed [[ptarmigan]]s).<ref>Hagen, C. A. and K. M. Giesen (2005). ''Lesser Prairie-Chicken (Tympanuchus pallidicinctus)'', version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref><ref>Johnson, J. A., M. A. Schroeder, and L. A. Robb (2011). ''Greater Prairie-Chicken (Tympanuchus cupido)'', version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref><ref>Bacon, B. R. (1981). ''Cooper's Hawk takes two prairie chickens off booming ground''. Passenger Pigeon, 43(5), 1.</ref> Juveniles usually are the more vulnerable and more regularly taken of non-quail galliforms by Cooper's hawks, but the hawks can take adults quite regularly despite the prey's relatively large size.<ref name=BOW/> Adult [[ruffed grouse]] (''Bonasa umbellus''), weighing an estimated mean of {{convert|619|g|lb|abbr=on}} when taken, are not infrequently exploited as prey, while adult [[sooty grouse]] (''Dendragapus fuliginosus''), estimated to weigh {{convert|1050|g|lb|abbr=on}} when taken have also been known to be taken repeatedly.<ref name= Hamerstrom/><ref name= Reynolds3/><ref name= Errington/><ref>Jewett, S. G. (1953). ''Birds of Washington state''. University of Washington Press.</ref><ref>Pelren, E. C., & Crawford, J. A. (1999). ''Blue grouse nesting parameters and habitat associations in northeastern Oregon''. The Great Basin Naturalist, 368–373.</ref> Adult male [[sharp-tailed grouse]] (''Tympanuchus phasianellus''), which average {{convert|1031|g|lb|abbr=on}}, are also known have been successfully preyed upon by Cooper's hawks.<ref>Moyles, D.L.J. (1979). ''Cooper's Hawk Attacks Sharp-Tailed Grouse''. Journal of Raptor Research, 13 (4): 120.</ref><ref>Swensen, J. E. & Eng, R.L. (1984). ''Autumn weights of Plains Sharp-tailed Grouse in Montana''. Prairie Naturalist, 16: 49–54.</ref> Even more impressive accounts show adult [[common pheasant]] estimated to weigh up to {{convert|1158|g|lb|abbr=on}} can be preyed upon by Cooper's hawks.<ref name= Ferguson-Lees/><ref name= Storer/> One [[wild turkey]] (''Meleagris gallopavo'') taken in Florida was cited with a weight of {{convert|5336|g|lb|abbr=on}}, which is the size of an adult. However, given that this is of enormous size relative to a Cooper's hawk, it would require verification that the turkey was this large and was taken alive by the hawk.<ref name= Millsap/> Not unexpectedly, turkey poults are known to fall prey to Cooper's hawks.<ref>Yeldell, N. A., Cohen, B. S., Little, A. R., Collier, B. A., & Chamberlain, M. J. (2017). ''Nest site selection and nest survival of eastern wild turkeys in a pyric landscape''. The Journal of Wildlife Management, 81(6), 1073–1083.</ref>

====Other birds====
Beyond aforementioned families and orders, other types of birds are taken relatively infrequently. Usually moderate to low numbers of [[water bird]]s are taken of any variety. About 5 species each of duck and [[heron]], a dozen species of [[Charadriiformes|shorebird]] and a smaller assortment of [[Eared grebe|grebes]] and [[Rail (bird)|rails]] are known in the prey spectrum.<ref name=BOW/><ref name= Cartron/><ref name= Sherrod/> Even among water birds, nonetheless, a wide diversity may be taken, from the tiny {{convert|22.9|g|oz|abbr=on}} [[least sandpiper]] (''Calidris minutilla'') to an adult [[mallard]] (''Anas platyrhynchos'') estimated to weigh {{convert|1150|g|lb|abbr=on}} when taken.<ref name= Reynolds3/><ref name= Sherrod/><ref name= CRC/><ref>Kus, B. E., Ashman, P., Page, G. W., & Stenzel, L. E. (1984). ''Age-related mortality in a wintering population of Dunlin''. The Auk, 101(1), 69–73.</ref><ref>Page, G., & Whitacre, D. F. (1975). ''Raptor predation on wintering shorebirds''. The Condor, 77(1), 73–83.</ref> Adult ducks and herons of roughly equal weight to Cooper's hawks and other largish adult water birds including [[ring-billed gull]]s (''Larus delewarensis'') and [[American coot]]s (''Fulica americana'') are sometimes tackled by these hawks.<ref name=BOW/><ref name= Millsap/><ref name= Cartron/><ref name= Stephens/><ref>Erskine, A. J. (1972). ''Buffleheads''. Canadian Wildlife Service Monograph Series 4.</ref> Particularly frequency was recorded of {{convert|312.7|g|oz|abbr=on}} [[western cattle egret]]s (''Ardea ibis'') in north Florida, where the egrets were the fourth most regularly recorded prey species.<ref name= Millsap/> Assorted families of land birds are fairly rare as reported in food studies, including some [[nightjar]]s, [[trogon]]s, [[Vaux's swift|swifts]], [[Belted kingfisher|kingfishers]], [[Red-necked parrot|parrots]] and assorted other raptorial birds.<ref name= Layne/><ref name= Millsap/><ref name= Reynolds3/><ref name= Kennedy2/><ref name= Haiman/><ref>Schwitters, L., D. Schwitters, E. L. Bull, and C. T. Collins (2019). ''Vaux's Swift (Chaetura vauxi)'', version 3.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref><ref>Williams, N. R. (2011). ''Elegant Trogon (Trogon elegans)'', version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref><ref name= Hiraldo>Hiraldo, F., Delibes, M., Bustamante, J., & Estrella, R. R. (1991). ''Overlap in the diets of diurnal raptors breeding at the Michilia Biosphere Reserve, Durango, Mexico''. J. Rap. Res., 25: 25–29.</ref><ref>Johnson, C. E. (1925). ''Kingfisher and Cooper's hawk''. The Auk, 42(4), 585–586.</ref>

===Mammals===
[[File:Juvenile Cooper&#039;s Hawk with Squirrel.jpg|thumb|left|A [[tree squirrel]] is an ample meal for a juvenile Cooper's hawk]]

A lower diversity of species and lower overall numbers of [[mammal]]s are taken relative to bird prey but mammalian prey can be locally important.<ref name= Reynolds3/> [[Chipmunk]]s are often regularly hunted in various regions, though only about one-third of North American chipmunks are known in the prey spectrum.<ref name= Reynolds3/><ref name= Kennedy2/><ref name= Hiraldo/><ref>Thorington Jr, R. W., Koprowski, J. L., Steele, M. A., & Whatton, J. F. (2012). ''Squirrels of the world''. JHU Press.</ref><ref>Hart, E. B. (1992). ''Tamias dorsalis''. Mammalian Species, (399), 1–6.</ref><ref>Best, T. L., & Granai, N. J. (1994). ''Tamias merriami''. Mammalian Species, (476), 1–9.</ref> High balances of the relatively large {{convert|96|g|oz|abbr=on}} [[eastern chipmunk]] (''Tamias striatus'') were found in studies from New York, Michigan and Wisconsin.<ref name= Hamerstrom/><ref name= Meng2/><ref name= Bielefeldt/> The eastern chipmunk appeared to dominate the foods of Cooper's hawks in the [[Green Ridge State Forest]] in [[Maryland]], at 49.1% of 57 prey items and mammals altogether made up an exceptional 66.9% of the foods.<ref name= Janik>Janik, C. A.  & Mosher, J.A. (1982). ''Breeding biology of raptors in the central Appalachians''. Raptor Res. 16:18–24.</ref> In the western United States, fewer chipmunks are identifiable but such prey is fairly commonly detected.<ref name= Kennedy2/><ref name= Kennedy3/> High balances of chipmunks were found in food studies from Oregon, especially in eastern Oregon where chipmunks (unidentified to species) were the leading prey type, at 22.5% of 120 prey items. The most common chipmunk prey in Oregon is probably the {{convert|89.3|g|oz|abbr=on}} [[Townsend's chipmunk]] (''Neotamias townsendii'') but Cooper's hawks may take chipmunks down to the size of the {{convert|48|g|oz|abbr=on}} [[least chipmunk]] (''Neotamias minimus'').<ref name= Reynolds3/><ref>Bergstom, B. (1999). ''Least Chipmunk (Tamias minimus)''. Pp. 366–369 in D Wilson, S Ruff, eds. Smithsonian Book of North American Mammals. Washington, D.C.: Smithsonian Institution Press in Association with the American Society of Mammalogists.</ref> Mammals distantly related to chipmunks, such as [[ground squirrel]]s (including [[antelope squirrel]]s) can be taken in locally high volume.<ref name= Palmer/> [[Golden-mantled ground squirrel]]s (''Callospermophilus lateralis'') were the second most important prey in eastern Oregon at 16.6%.<ref name= Reynolds3/> [[Thirteen-lined ground squirrel]]s (''Ictidomys tridecemlineatus'') were the second most common prey species in a study from Wisconsin and also important in the diet in [[North Dakota]] (where they were the most significant contributor of biomass, constituting 23.4%).<ref name= Errington/><ref name= Stephens/><ref>Schwagmeyer, P. L. (1980). ''Alarm calling behavior of the thirteen-lined ground squirrel, Spermophilus tridecemlineatus''. Behavioral Ecology and Sociobiology, 7(3), 195–200.</ref> Golden-mantled and thirteen-lined ground squirrels are fairly small for ground squirrels, the earlier averaging {{convert|166|g|oz|abbr=on}}, the latter of similar size.<ref name= Reynolds3/> A few larger ground squirrels may be hunted, such as [[California ground squirrel]]s (''Otospermophilus beecheyi'') and [[rock squirrel]]s (''Otospermophilus variegatus''), both averaging over {{convert|600|g|lb|abbr=on}} in adults, albeit infrequently.<ref name= Boal3/><ref>Hanson, M. T., & Coss, R. G. (1997). ''Age differences in the response of California ground Squirrels (Spermophilus beecheyi) to avian and mammalian predators''. Journal of Comparative Psychology, 111(2), 174.</ref> [[Tree squirrel]]s are widely taken but secondary prey for Cooper's hawks. The smallish, roughly {{convert|200|g|oz|abbr=on}} [[American red squirrel]] (''Tamiasciurus hudsonicus'') are not infrequent prey in northerly locations. About 36 red squirrels were recorded in the foods of Cooper's hawk in Ithaca, New York and these squirrels appear to have specific alarm calls that are provoked by these hawks, however the rate of predation by Cooper's appears to be low relative to other predators overall.<ref name= Meng2/><ref>Greene, E., & Meagher, T. (1998). ''Red squirrels, Tamiasciurus hudsonicus, produce predator-class specific alarm calls''. Animal Behaviour, 55(3), 511–518.</ref><ref>Schauffert, C. A., Koprowski, J. L., Greer, V. L., Alanen, M. I., Hutton, K. A., & Young, P. J. (2002). ''Interactions between predators and Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis)''. The Southwestern Naturalist, 47(3), 498–501.</ref> Reported when taking red squirrels, male Cooper's hawks, being relatively small, may tear the prey into pieces that can be transported by them to the nest.<ref name= Brown/> Numerous other tree squirrels are taken occasionally by Cooper's hawks.<ref name= Cartron/><ref name= Estes/><ref name= Reynolds3/><ref>Kneeland, M. C., Koprowski, J. L., & Corse, M. C. (1995). ''Potential Predators of Chiricahua Fox Squirrels (Sciurus nayaritensis chiricahuae)''. The Southwestern Naturalist, 40(3), 340–342.</ref> Sizes of tree squirrels taken by Cooper's hawks were studied in Missouri. [[Eastern gray squirrel]]s (''Sciurus carolinensis'') were taken of up to adult size but [[fox squirrel]]s (''Sciurus niger'') were only taken as juveniles, as the adults, sometimes scaling up to {{convert|1350|g|lb|abbr=on}}, were apparently too formidable for Cooper's. The estimated weights of both the gray and fox squirrels taken in Missouri was {{convert|450|g|oz|abbr=on}}, with the gray contributing 10.9% of the biomass.<ref name= Toland/>

About 20 non-sciurid rodent species may be taken by Coopers hawks but are rarely significant in the foods. Both American species of [[flying squirrel]]s, [[Pack rat|woodrat]]s, commoner ''[[Peromyscus]]'' mice, some species of [[vole]] and [[lemming]], [[cotton rat]]s, [[jumping mice]], [[Ord's kangaroo rat|kangaroo rats]] and non-native rodents may all be prey occasionally, although most species of these are fairly [[Nocturnality|nocturnal]] and thus of limited access.<ref name= Cartron/><ref name= Layne/><ref name= Sherrod/><ref name= Haiman/><ref name= Boal3/><ref name= Reynolds4/> Few of these types of rodents are taken frequently enough to warrant much individual mention. Unidentified woodrats, at a mean estimated mass of {{convert|256.6|g|oz|abbr=on}} were significant to the biomass of Cooper's hawks in northwestern Oregon.<ref name= Reynolds3/> In North Dakota, ''Peromyscus'' mice made up an unusually high 13.5% of the foods.<ref name= Stephens/> In the city of [[Burnaby]], when bird feeders began to attract [[black rat]]s (''Rattus rattus''), Cooper's hawk's came to locally take significant numbers of both young and adult rats.<ref name= McNicholl/> The first verified predation by a Cooper's hawk on a [[brown rat]] (''Rattus norvegicus'') was recently reported, also in British Columbia.<ref name= Stirling>Stirling, D. (2011). ''Cooper's Hawk Feeding on Barred Owl and Norway Rat in Victoria, British Columbia''. Wildlife Afield 8(1):120–122.</ref> One broad study found a somewhat unexpected correlation was found positively relating the previous summer's rodent density to the number of Cooper's hawks. This could be coincidental as rodent populations are probably driven by [[acorn]] production in the year prior to the rodent increases, and many of the birds taken regularly by Cooper's are also partially acorn dependent.<ref>Schmidt, K. A., & Ostfeld, R. S. (2003). ''Songbird populations in fluctuating environments: predator responses to pulsed resources''. Ecology, 84(2), 406–415.</ref> Occasionally, Cooper's hawks may capture profitable mammalian prey such as [[Leporidae|rabbits and hares]]. Mainly, predation has been reported on the [[cottontail rabbit]]s. Strong numbers of [[mountain cottontail]] (''Sylvilagus nuttallii''), averaging about {{convert|716|g|lb|abbr=on}} when taken, were reported in northwestern Oregon (7.82% and fifth most regular prey species).<ref name= Reynolds3/> In the rural vicinity of Tucson, cottontail rabbits were the second most regularly selected type of prey, at 12.7%.<ref name= Boal/> Fairly strong numbers of cottontails were also reported in [[New Mexico]] and [[Durango]].<ref name= Kennedy3/><ref name= Hiraldo/> In Missouri, the widely found [[eastern cottontail]] (''Sylvilagus floridanus'') was the most significant contributor of biomass, making up 14.5% of the total biomass.<ref name= Toland/> On average, in Missouri, the body mass of eastern cottontails caught was {{convert|600|g|lb|abbr=on}}, indicating juvenile eastern cottontails are usually caught.<ref name= Toland/> However, there are several known cases of adult eastern cottontails falling prey to Cooper's hawks, including cottontails estimated to weigh from {{convert|1100|to|1290|g|lb|abbr=on}}.<ref name= Millsap/><ref name= Storer/> Various species of non-cottontail leporids may occasionally be caught, including young [[black-tailed jackrabbit]]s (''Lepus californicus''), [[pygmy rabbit]]s (''Brachylagus idahoensis'') as well as fairly large numbers of feral [[European rabbit]]s (''Oryctolagus cuniculus'') in [[Victoria, British Columbia]].<ref name= Palmer/><ref name= Cava/><ref>Larrucea, E. S., & Brussard, P. F. (2009). ''Diel and seasonal activity patterns of pygmy rabbits (Brachylagus idahoensis)''. Journal of Mammalogy, 90(5), 1176–1183.</ref>

Mammals of other orders are taken quite infrequently, with a low volume of [[American short-tailed shrew|shrews]] and [[Mole (animal)|mole]]s reported.<ref name= Palmer/><ref name= Sherrod/><ref name= Reynolds3/> Cooper's hawks are considered a potential predator of the smaller species of [[weasel]] and were recorded in Florida to kill a [[striped skunk]] (''Mephitis mephitis'') kit estimated to weigh about {{convert|661|g|lb|abbr=on}}.<ref name= Millsap/><ref>Linnell, M. A., Epps, C. W., Forsman, E. D., & Zielinski, W. J. (2017). ''Survival and predation of weasels (Mustela erminea, Mustela frenata) in North America''. Northwest science, 91(1), 15–26.</ref> Occasionally, Cooper's hawks are known to hunt bats. They are said to usually capture bats on the wing rather than search them out.<ref name= Palmer/><ref name=BOW/><ref>{{cite journal|last1=Mikula|first1=P.|last2=Morelli|first2=F.|last3=Lučan|first3=R. K.|last4=Jones|first4=D. N.|last5=Tryjanowski|first5=P.|year=2016|title=''Bats as prey of diurnal birds: a global perspective''|journal=Mammal Review|volume=46|issue=3|page=160|doi=10.1111/mam.12060|bibcode=2016MamRv..46..160M }}</ref> Findings were that in [[Carlsbad Caverns National Park|Carlsbad Caverns]] that Cooper's (and also sharp-shinned) hawks were the most efficient avian predators of bats near the cave entrance (rating as more successful than most ''Buteo'' hawks and particularly more so than larger and less agile raptors like [[red-tailed hawk]]s and [[Great horned owl|large owls]]). Per observation in Carlsbad, due to their agility, Cooper's can match the evasive flight of a bat and may be successful in about 90% of observed pursuits.<ref>Baker, J. K. (1962). ''The manner and efficiency of raptor depredations on bats''. The Condor, 64(6), 500–504.</ref> Apart from their well-documented predation of [[Mexican free-tailed bat]]s (''Tadarida brasiliensis''), quite little is known about which bat species Cooper's hawk's may prey upon and at what level do the local hawks depend on such prey. Apart from caves, sometimes Cooper's hawks have been seen to capture bats in urbanized areas.<ref name= Palmer/><ref name= Clark2/><ref>Leopold, A. S. (1944). ''Cooper's hawk observed catching a bat''. The Wilson Bulletin, 56(2), 116.</ref><ref>Sprunt Jr., A. (1950). ''Hawk predation at the bat caves of Texas''. Texas J. Sci, 2 (4): 462–470.</ref>

===Other prey===
In some areas, respectable numbers of reptiles may be hunted. All told, nearly 30 species of reptile may be hunted by Cooper's hawks.<ref name= Palmer/><ref name= Haiman/><ref name= Hiraldo/> In the eastern part of the range, even in biodiverse locations for reptilian species such as Florida, a very low volume of such prey are reportedly taken by Cooper's hawks.<ref name= Toland/><ref name= Millsap/> In [[Arkansas]], a small sample of road-killed Cooper's hawks showed that small reptiles were more common than birds amongst the stomach contents, with [[Bougainville's skink]]s (''Lerista bougainvillii'') and [[ring-necked snake]]s (''Diadophis punctatus'') constituting about 40% of the diet.<ref name= Hanebrink>Hanebrink, E. L., Posey, A. F., & Sutton, K. B. (1979). ''Note on the Food Habits of Selected Raptors from Northeastern Arkansas''. Journal of the Arkansas Academy of Science, 33(1), 79–80.</ref> Strong detection of reptilian prey is known in more western locations, especially farther south.<ref name=BOW/> In fact, of avian predators in one Californian study's estimation, Cooper's hawks showed the most reliance on lizards locally, but that Cooper's was not locally common in the study area so had relatively limited impact.<ref>Jaksić, F. M., & Greene, H. W. (1984). ''Empirical evidence of non-correlation between tail loss frequency and predation intensity on lizards''. Oikos, 407–411.</ref> In California, it was found that 69% of the diet was reptiles, most of which were assorted lizards (led by [[Aspidoscelis|whiptail lizard]]s, nearly {{convert|2.8|kg|lb|abbr=on}} of which were estimated to be found in one nest).<ref name= Fitch2/><ref>Husak, J. F., Macedonia, J. M., Fox, S. F., & Sauceda, R. C. (2006). ''Predation cost of conspicuous male coloration in collared lizards (Crotaphytus collaris): an experimental test using clay‐covered model lizards''. Ethology, 112(6), 572–580.</ref> In rural areas outside of Tucson, a fairly strong presence of (unidentified to species) [[spiny lizard]]s, at 13% of 77 prey items, although overall in all areas of the Tucson metropolitan, reptiles constituted a lower 8% of the total 228 prey items.<ref name= Estes/> In [[Durango]], reptiles were a pronounced part of Cooper's hawk diet. Here, the most frequently identified prey species was the [[Mexican Plateau horned lizard]] (''Phrynosoma orbiculare'') (11.5% of 191 prey items), followed by the northern flicker and thirdly the [[Sceloporus poinsettii|crevice spiny lizard]] (''Sceloporus poinsettii'') (10.47%, plus other unidentified spiny lizards making up a further 4.2% of the diet).<ref name= Hiraldo/> In Arizona, spiny lizards were similarly detected to have a strong prey-predator relationship with Cooper's hawks as well.<ref>Ballinger, R. E. (1979). ''Intraspecific variation in demography and life history of the lizard, Sceloporus jarrovi, along an altitudinal gradient in southeastern Arizona''. Ecology, 60(5), 901–909.</ref> Most lizards encountered and hunted by Cooper's hawks are fairly small but, despite being more scarcely selected, snake prey may show greater size variation.<ref name= Toland/><ref name= Millsap/><ref name= Hiraldo/> Snakes known to be taken have ranged in size from the {{convert|6|g|oz|abbr=on}} [[Storeria occipitomaculata|redbelly snake]] (''Storeria occipitomaculata'') to the a young [[Pantherophis obsoletus|black rat snake]] (''Pantherophis obsoletus''), estimated to weigh {{convert|200|g|oz|abbr=on}}, and the [[Pituophis catenifer|gopher snake]] (''Pituophis catenifer'') (adults of the latter two snake species can average roughly {{convert|890|g|lb|abbr=on}} for both species and may be too formidable for these hawks).<ref name= Palmer/><ref name= Toland/><ref name= Hanebrink/><ref>Linzey, D.W. & Clifford, M.J. (1981). ''Snakes of Virginia''. Univ. of Virginia Press, Charlottesville, VA.</ref><ref>Kaufman, G. A., & Gibbons, J. W. (1975). ''Weight-length relationships in thirteen species of snakes in the southeastern United States''. Herpetologica, 31–37.</ref> Unlike with reptiles, there is little evidence that Cooper's hawk regularly hunts [[amphibian]]s in any area, despite a few species being known in the prey spectrum.<ref name= Palmer/><ref name= Hiraldo/><ref>Cook, W. E. (1987). ''Amphibians and reptiles: predators and prey. Amphibians and birds''. Smithsonian Herpetological Information Service.</ref> While some authors have posited that as much as 2.1% of Cooper's hawks' global prey consists of [[invertebrate]]s,<ref name= Palmer/><ref name= Jones/> prevailing food studies tend to find scant to none evidence of such prey;<ref name=BOW/><ref name= Sherrod/> however, a truly exceptional case of Cooper's hawks found dead in Arkansas showed that [[beetle]]s and [[moth]]s/[[butterflies]] each represented 12.5% of detected prey items.<ref name= Hanebrink/>

===Interspecific predatory relationships===
[[File:Circus hudsonius chasing Accipiter cooperii.jpg|thumb|left|Other raptors can be intolerant of sharing resources with Cooper's hawks, the likely reason this [[northern harrier]] is chasing this young Cooper's hawk.]]
Of special interest is how Cooper's hawks live alongside [[sharp-shinned hawk]]s and [[American goshawk]]s. Little distinguishes outright the distribution, habitat, ecology and prey spectrum of sharp-shinned hawks from Cooper's hawks. Throughout the range of Cooper's hawk, sharp-shins may be found breeding, migrating and wintering in similar areas. So too is there much overlap between the ranges of Cooper's hawks and American goshawks, such as throughout southern Canada, the western United States, the Upper Midwest (and sometimes in the Northeastern United States) and during times of passage.<ref name= Ferguson-Lees/><ref name=BOW/> In general, sharp-shinned hawks tend to use younger and denser stands of trees than do Cooper's. Meanwhile, goshawks tend to favor [[old-growth forest]] area with taller and older trees and generally lower tree densities.<ref name=BOW/><ref name= Reynolds/> However, all three species prefer fairly enclosed canopies over their nesting areas, i.e. canopy coverage are generally thought to need to be at least at 60–70%.<ref name=James/> A particular opportunity was taken to study the three hawks' ecology when living near one another in Oregon. Unusually, nests were not consistently well spaced between the species, and 2 sharp-shin nests were approximately {{convert|300|m|ft|abbr=on}} from active Cooper's nests, while 5 Cooper's nests were {{convert|300|to|450|m|ft|abbr=on}} from active goshawk nests.<ref name= Reynolds2/> However, the patch habitat and dietary behavior of each species was still fairly partitioned.<ref name= Reynolds2/><ref name= Reynolds3/> Here, for sharp-shinned hawks, the tree stands averaged 22–50 years old and had a mean density of 1180 trees per hectare (ha), while Cooper's stands averaged 30–70 years old and had a mean of 907 trees per ha while the goshawk used in oldest and most open stands, with trees of an average age of 150 years, and a mean of 482 trees per ha.<ref name= Reynolds2/><ref name= Reynolds5>Reynolds, R. T. (1983). ''Management of western coniferous forest habitat for nesting accipiter hawks''. U.S. Dep. Agric. For. Serv. Rocky Mtn. For. and Range Exp. Stn.</ref> The data from the [[Jemez Mountains]] of [[New Mexico]] was largely corresponding with the goshawk occurring in areas with a median of 781 trees per ha, Cooper's in areas with a median of 1229 trees per ha and the sharp-shins in a median of 1482 tree per ha. In the New Mexico data, goshawks used the largest trees with the lowest median canopy coverage (77.4% vs 78.4% for Cooper'
s and 83.1% for sharp-shins).<ref name= Siders>Siders, M. S., & Kennedy, P. L. (1994). ''Nesting habitat of Accipiter hawks: is body size a consistent predictor of nest habitat characteristics?'' Studies in Avian Biology, 16, 92–96.</ref> In a study from northern Utah, Cooper's hawks were intermediate in most habitat characteristics, being at median elevation ({{convert|1782|m|ft|abbr=on}}), nest height ({{convert|8|m|ft|abbr=on}} against {{convert|6|m|ft|abbr=on}} for sharp-shins and {{convert|12|m|ft|abbr=on}} for goshawk) and in areas of intermediate branch density. However, Cooper's nests were the closest in Utah to areas disturbed by humans ({{convert|147|m|ft|abbr=on}} against {{convert|161|m|ft|abbr=on}} for sharp-shinned and {{convert|250|m|ft|abbr=on}} for goshawk), also closest to water ({{convert|220|m|ft|abbr=on}} against {{convert|444|m|ft|abbr=on}} in sharp-shins and {{convert|394|m|ft|abbr=on}} for goshawk).<ref>Hennessy, S. P. (1978). ''Ecological relationships of accipiters in northern Utah-with special emphasis on the effects of human disturbance''. M.S. Thesis, Utah State Univ., Logan.</ref> There is often some level of distinction in habitat between Cooper's and the sharp-shinned hawk. Compared to sharp-shinned hawks in Wisconsin and Oregon, Cooper's hawks use woods with fewer conifers, less dense stands of trees and stands with taller trees. Often, sharp-shinned hawk nests are lower in the trees and placed in much denser vegetation (often even the sharp-shins with their smaller frames themselves accidentally strike against branches while attempting to enter the nest), to hide the nest more sufficiently against predators.<ref name= Reynolds2/><ref name= Trexel>Trexel, D. R., Rosenfield, R. N., Bielefeldt, J., & Jacobs, E. A. (1999). ''Comparative nest site habitats in Sharp-shinned and Cooper's hawks in Wisconsin''. The Wilson Bulletin, 7–14.</ref><ref name= Snyder3>Snyder, N. F., & Snyder, H. A. (1992). ''Biology of North American accipiters in the Chiricahua Mountains''. In Proceedings of the Chiricahua Mountains Research Symposium, ed. AM Barton and SA Sloan. Southwest Parks and Monuments Association. Tucson (pp. 91–94).</ref> The habitat used by the two species in [[Missouri]] was less distinct (i.e. similar tree species used). However, the sharp-shinned hawk nests in Missouri were at much higher elevations, i.e. {{convert|343|m|ft|abbr=on}} above sea level, than those of Cooper's (which were at a mean elevation of {{convert|151.3|m|ft|abbr=on}}; more surprisingly the stand density was higher here for Cooper's, at a mean of 935.7 trees per ha than those used by sharp-shins, at a mean of 599.3 trees per ha.<ref name= Wiggers>Wiggers, E. P. & Kritz, P.J. (1991). ''Comparison of nesting habitat of coexisting Sharp-shinned and Cooper's hawks in Missouri''. Wilson Bulletin, 103: 568–577.</ref> There was some level of temporal differences between the two species in study in Indiana, where Cooper's hawks were generally active in the early morning but sharp-shinned hawks did not become active until later in the morning (hypothetically to avoid more severe interguild predation by large owls due to its smaller size).<ref name= Roth/> In northern New Jersey, compared to nesting goshawks, Cooper's hawks used flatter lands that were closer to roads, other openings and human habitations. However, canopy coverage averaged high in New Jersey data for Cooper's, at 89.1%.<ref name= Bosakowski>Bosakowski, T., Smith, D. G., & Speiser, R. (1992). ''Nest sites and habitat selected by Cooper's hawks, Accipiter cooperii, in northern New Jersey and southeastern New York''. Canadian Field-Naturalist. Ottawa ON, 106(4), 474–479.</ref>

Cooper's hawk has a mean home range size that was comparable to the roughly half as large-bodied [[Eurasian sparrowhawk]], at {{convert|1190|ha|acre|abbr=on}} for Cooper's and {{convert|835|ha|acre|abbr=on}} for the sparrowhawk. However, data shows that in North America, the home range size of ''Accipiter'' and ''Astur'' species corresponded to the birds' body size, i.e. {{convert|2600|ha|acre|abbr=on}} mean for the goshawk and {{convert|458|ha|acre|abbr=on}} mean for the sharp-shinned hawk.<ref name= Reynolds4/> The aforementioned Oregon studies also studied at length the dietary differences between the three American ''Accipiter''/''Astur'' hawk species. Cooper's hawks prey sizes were intermediate in keeping with body size, at around {{convert|135|g|oz|abbr=on}} versus a mean prey size of {{convert|306.6|g|oz|abbr=on}} for the goshawk in eastern Oregon and {{convert|12.8|and|28.4|g|oz|abbr=on}} for sharp-shins in northwestern and eastern Oregon, respectively.<ref name= Reynolds3/> The amount of mammals in the diet in Oregon also increased with the body size of the species.<ref name= Reynolds3/><ref name= Reynolds4/> The diets of the three species were also studied in the [[Chiricahua Mountains]] of Arizona. There was some diet overlap in preferred prey for Cooper's hawks with both the sharp-shinned hawk and the American goshawk. In the case of the goshawk and Cooper's, both hawks regularly took [[Steller's jay]]s and [[band-tailed pigeon]]s (''Patagioenas fasciata''). With the sharp-shinned hawk, Cooper's locally also shared a liking for [[American robin]]s and [[black-headed grosbeak]]s (''Pheucticus melanocephalus''). However, unlike either the sharp-shinned hawk or the goshawk in the Chiricahuas, Cooper's hawks regularly took chipmunks and lizards as well.<ref name= Snyder3/> Furthermore, the nests of Cooper's and goshawks were fairly evenly spaced, at about {{convert|1.6|km|mi|abbr=on}} apart, indicating that they maintain exclusive territories (almost as if within the same species), while sharp-shinned hawk nests were closer to goshawk nests but in much denser habitats.<ref name= Snyder3/> When chickens were experimentally exposed to each of the three American ''Accipiters'', they reacted the most aggressively to the sharp-shinned hawk (as they pose little to no threat to adult poultry), intermediately to Cooper's and with strong attempts to evade and escape when exposed to the goshawk, which is very capable and ready to dispatch adult poultry.<ref>Palleroni, A., Hauser, M., & Marler, P. (2005). ''Do responses of galliform birds vary adaptively with predator size?'' Animal Cognition, 8(3), 200–210.</ref> Many studies have contrasted the diet of Cooper's and sharp-shinned hawk in other areas as well, with the sharp-shinned hawk much more regularly selecting birds weighing under about {{convert|28|g|oz|abbr=on}}, a fair amount overlap in birds of {{convert|28|to|40|g|oz|abbr=on}} and {{convert|40|to|75|g|oz|abbr=on}} weight classes but birds over this weight range are increasingly more often taken almost exclusively by Cooper's.<ref name= Palmer/><ref name= Storer/><ref name= Reynolds3/><ref name= Roth4>Roth, T. C., Lima, S. L., & Vetter, W. E. (2006). ''Determinants of predation risk in small wintering birds: the hawk's perspective''. Behavioral Ecology and Sociobiology, 60(2), 195–204.</ref> Also, the sharp-shinned hawk appears to hunt more so birds that dwell at the canopy level in the woodlands (as opposed to ground to shrub height-dwelling birds) within the forest and prefers to attack in heavier cover than Cooper's seemingly.<ref name= Roth2/><ref name= Reynolds3/><ref name= Roth3/>

[[File:Mockingbird dive bombing Cooper&#039;s Hawk (35598944133).jpg|thumb|A [[Northern mockingbird|mockingbird]] flying in to dive-bomb a Cooper's hawk]]

The ecology of Cooper's hawks has also been studied in contrast to other diurnal raptors as well. In the raptor guild within southern Michigan, the overall food breadth and size was studied against [[red-tailed hawk]]s, [[red-shouldered hawk]]s and [[American kestrel]]s. Here, although the food niche breadth (mean number of prey species per study site) of Cooper's was relatively low at 1.79, Cooper's hawk had the largest mean prey sizes at {{convert|67.4|g|oz|abbr=on}}, which was considerably higher than even the much larger red-tailed hawk (mean prey mass of {{convert|43.4|g|oz|abbr=on}}).<ref name= Craighead/><ref name="Jaksic">Jaksić, F. M., & Braker, H. E. (1983). ''Food-niche relationships and guild structure of diurnal birds of prey: competition versus opportunism''. Canadian Journal of Zoology, 61(10), 2230–2241.</ref> In southern Wisconsin, the food niche breadth was rather higher for Cooper's at 6.9 and the mean prey mass, at {{convert|109.9|g|oz|abbr=on}}, was second only to the red-tailed hawk's. In the Wisconsin data, the red-shouldered, the [[Broad-winged hawk|broad-winged]] and [[rough-legged hawk]]s (''Buteo lagopus'') as well as the [[northern harrier]], [[peregrine falcon]] (''Falco peregrinus'') and the American kestrel all had lower mean prey masses.<ref name= Jaksic/> Much farther south in Durango, Mexico, while there was overlap in the [[Class (biology)|class]] of prey selected by Cooper's hawks with the other studied raptor species, American kestrels, red-tailed and [[zone-tailed hawk]]s (''Buteo albonotatus''), there was minimal overlap in which prey species were usually selected, especially given the difference in habitat usage. Furthermore, in Durango, while Cooper's and the ''Buteo'' hawks all took appreciable numbers of adult [[cotton rat]]s, kestrels selected only young cotton rats.<ref name= Hiraldo/> In a study in western Maryland, Cooper's hawks used more mature woodland with a more developed understory and more extensive ground cover than the other woodland nesting hawks, the broad-winged and red-shouldered hawks. While red-tailed hawks nested fairly high in the Maryland data in isolated pines somewhat out of the interior forest, Cooper's nests were at similar height in forest and slightly higher than those of red-shouldered hawks and much higher than those of broad-winged hawks.<ref name= Titus/> In what was probably a case of defense of their hunting ground, a female Cooper's hawk was recorded to attack and drive off (without physical contact) a larger peregrine falcon from a perch during winter in Ontario.<ref>Horvath, R. (2009). ''Presumed Defense of Hunting Territory by a Cooper's Hawk''. Ontario Birds.</ref>

Cooper's hawk is usually a top predator in the daytime but is not immune from attack by other predators.<ref name=BOW/><ref name= Fremlin>Fremlin, K. (2018). ''Trophic magnification of legacy persistent organic pollutants and emergent contaminants within a terrestrial food-web of an avian apex predator, the Cooper's Hawk (Accipiter cooperii)'' (Doctoral dissertation, Science: Biological Sciences Department).</ref> The most common predator of this species is almost certainly the [[great horned owl]] (''Bubo virginianus''). This rather large owl (averaging more than three times heavier than a Cooper's hawk) is known to regularly track down fledglings and adults as well as raid the nests of other birds of prey. Many records show great horned owls will visit the nests of birds of prey and pick off the young nightly until the prey resource is exhausted (i.e. all young or sometimes adult birds of prey are killed).<ref>Marti, C. D., & Kochert, M. N. (1996). ''Diet and Trophic Characteristics of Great Horned Owls in Southwestern Idaho''. Journal of Field Ornithology, 499–506.</ref><ref name= Voous>{{cite book | last1 =Voous | first1 = Karel H. | author-link = Karel H. Voous |author2 = Cameron, Ad (illustrator) |title = ''Owls of the Northern Hemisphere''| year = 1988 | publisher = London, Collins | isbn =978-0-00-219493-8|pages =209–219}}</ref><ref name= Smith3>Smith, D. G. (2002). ''Great Horned Owl''. Stackpole Books.</ref> Furthermore, given the opportunity, great horned owls readily expropriate the nests built by the raptors they kill as their own.<ref name= Voous/><ref name= Smith3/> Given its preference for secluded wooded spots near woodland openings, Cooper's hawks are frequently the subject of unwanted attention from horned owls.<ref name=BOW/><ref name= Wiley>Wiley, J. W. (1975). ''Relationships of nesting hawks with Great Horned Owl''. The Auk, 92(1), 157–159.</ref> Both the young, especially around the time they leave the nest or are recently fledged, and adult Cooper's hawks are vulnerable to these owls.<ref name=BOW/><ref name= Reynolds3/><ref>Phillips, C., & Ricard, P. (1996). ''Cooper's Hawk and Great Horned Owl encounter''. Bird Observer, 24: 36–37.</ref> While little data has been collected on the overall effect great horned owls have on Cooper's hawk populations, it is known that for the larger, more formidable goshawk that as many as 40% of radiotagged juveniles within a study appeared to meet their demise via horned owls.<ref name=BOW/><ref>Ward, J. M., & Kennedy, P. L. (1996). ''Effects of supplemental food on size and survival of juvenile Northern Goshawks''. The Auk, 200–208.</ref> Due to their threat level, the calls of great horned owls provoke a strong response from Cooper's hawks and banders and researchers usually use stimuli of great horned owls to attract a mobbing Cooper's hawks.<ref>Miller, L. (1952). ''Auditory recognition of predators''. The Condor, 54(2), 89–92.</ref><ref>Bloom, Peter, Henckel, J., Henckel, E., Schmutz, J., Woodbridge, B., Bryan, J., Anderson, R. & Detrich, P. (1992). ''The dho-gaza with great horned owl lure: an analysis of its effectiveness in capturing raptors''. Journal of Raptor Research. 26: 167–178.</ref> Reportedly, Cooper's hawks will temporarily tolerate and possibly even cooperate with crows when one or the other spots a great horned owl in the daytime, both species appearing to join forces to mob the threatening owl out of the vicinity.<ref name= Palmer/><ref name= Wiley/> In one case, after a great horned owl pair failed to successfully breed in a nest built by other Cooper's hawks, a pair of Cooper's who tried to nest was supplanted by horned owls, possibly of the same pair who had previously failed.<ref name= Wiley/>

Other natural predators of Cooper's hawks that are known are mainly larger diurnal birds of prey. In some cases, their larger cousins, American goshawks, will prey on Cooper's hawks.<ref name=BOW/><ref name= Cartron/><ref name= Snyder3/> Widely but somewhat scarcely, red-tailed hawks have been known to prey on Cooper's hawk, while a single instance is known of a Cooper's falling prey to a [[golden eagle]] (''Aquila chrysaetos'').<ref name= Stout3>Stout, W. & Rosenfield, R. & Holton, W.G. & Bielefeldt, J. (2006). ''The status of breeding Cooper's Hawks in the metropolitan Milwaukee area''. Passenger Pigeon, 68:309–320.</ref><ref>Peyton, S. B. (1945). ''Western Red-tailed Hawk catches Cooper's Hawk''. Condor, 47: 167.),</ref><ref>Olendorff, R. R. (1976). ''The food habits of North American golden eagles''. American Midland Naturalist, 231–236.</ref> Less is known about the range of nest predators. Among all known predators, only the [[raccoon]] (''Procyon lotor'') can be considered to rival the great horned owl as the most severe threat to nesting attempts, probably consuming mostly nestlings and eggs but also perhaps some older hawks.<ref name= Palmer/><ref name= Meng/><ref name= Rosenfield8/><ref name= Stout2>Stout, W. E., Rosenfield, R. N., Holton, W. G., & Bielefeldt, J. (2007). ''Nesting biology of urban Cooper's Hawks in Milwaukee, Wisconsin''. The Journal of Wildlife Management, 71(2), 366–375.</ref> American crows are known to rob nests of Cooper's hawks as well, especially when the parents have been displaced by the crow's severe mobbing.<ref name= Palmer/> Smaller diurnal birds of prey are, in turn, threatened by Cooper's hawks. This is especially the case with the American kestrel. After some regional declines, a radiotagging study in Pennsylvania found that of 19 kestrels, 26% were killed by avian predators, with the suspected culprit in a majority of the cases being Cooper's hawks.<ref>Farmer, G. C., McCarty, K., Robertson, S., Robertson, B., & Bildstein, K. L. (2006). ''Suspected predation by accipiters on radio-tracked American Kestrels (Falco sparverius) in eastern Pennsylvania, USA''. Journal of Raptor Research, 40(4), 294–297.</ref><ref>C. Michael Hogan, ed. 2010. [http://www.eoearth.org/article/American_kestrel ''American Kestrel'']. Encyclopedia of Earth, U.S. National Council for Science and the Environment, Ed-in-chief C. Cleveland</ref> Some resources have gone as far as to blame the kestrels decline directly on Cooper's hawk predation but subsequent data from the [[Breeding bird survey|U.S. Breeding Bird Survey]] and the [[Christmas Bird Count|National Audubon Society Christmas Bird Count]] appear to discount this theory, instead linking the overall declines to inadvertent human causes.<ref name= McClure>McClure, C. J., Schulwitz, S. E., Van Buskirk, R., Pauli, B. P., & Heath, J. A. (2017). ''Commentary: Research recommendations for understanding the decline of American Kestrels (Falco sparverius) across much of North America''. Journal of Raptor Research, 51(4), 455–464.</ref><ref name= Lesko>Lesko, M. J., & Smallwood, J. A. (2012). ''Ectoparasites of American Kestrels in northwestern New Jersey and their relationship to nestling growth and survival''. Journal of Raptor Research, 46(3), 304–313.</ref> Cooper's hawk are also counted as a predator of [[Merlin (bird)|merlins]] (''Falco columbarius'').<ref>Warkentin, I. G., N. S. Sodhi, R. H. M. Espie, A. F. Poole, L. W. Oliphant, and P. C. James (2005). ''Merlin (Falco columbarius)'', version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> The only confirmed accipitrid that Cooper's hawk have been known to prey upon is their smaller cousins, the sharp-shinned hawks.<ref name=BOW/><ref name= Roth3/> However, in the [[Southeastern United States|southeast]], Cooper's hawks was counted among the potential, but not yet confirmed, predators of [[swallow-tailed kite]]s (''Elanoides forficatus'') and nesting kites appear to engage in anti-predator behavior towards Cooper's hawks.<ref>Coulson, J. O., Coulson, T. D., DeFrancesch, S. A., & Sherry, T. W. (2008). ''Predators of the Swallow-tailed Kite in southern Louisiana and Mississippi''. Journal of Raptor Research, 42(1), 1–12.</ref> Furthermore, Cooper's hawks that came into the vicinity were considered potential predators and mobbed as such by nesting [[gray hawk]]s.<ref>Stensrude, C. (1965). ''Observations on a pair of Gray Hawks in southern Arizona''. The Condor, 67(4), 319–321.</ref>

Even more so than diurnal raptors, a wide diversity of owls are known to fall prey to Cooper's hawks. Despite the temporal differences of their activity, the intensive hunting methods of Cooper's hawks may allow them to access roosting owls more readily than other types of hawks.<ref name= Palmer/><ref name=BOW/> Small owls that Cooper's hawk have been known to prey upon have included [[flammulated owl]]s (''Psiloscops flammeolus''),<ref>McCallum, D. A. (1994). ''Review of technical knowledge: Flammulated owls''. In: Hayward, GD and J. Verner, tech. editors. ''Flammulated, boreal, and great gray owls in the United States: A technical conservation assessment''. Gen. Tech. Rep. RM-253. Fort Collins, CO: US Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. p. 14-46, 253.</ref><ref>Borell, A. E. (1937). ''Cooper's hawk eats a flammulated screech owl''. Condor, 39, 44.</ref> [[eastern screech-owl]]s (''Megascops asio''),<ref name= Sherrod/> [[western screech-owl]]s (''Megascops kennicottii''),<ref name= Cartron/> [[whiskered screech-owl]] (''Megascops trichopsis''),<ref>Gehlbach, F. R., N. Y. Gehlbach, P. Pyle, and M. A. Patten (2017). ''Whiskered Screech-Owl (Megascops trichopsis)'', version 3.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> [[elf owl]] (''Micrathene whitneyi''),<ref>Ligon, J. D. (1968). ''The biology of the Elf Owl (Micrathene whitneyi)''. Misc. Publ., Mys. Zool., Univ. Mich. 136.</ref> [[northern pygmy owl]] (''Glaucidium gnoma''),<ref>Darling, L. M. (2003). ''Status of the Vancouver Island Northern Pygmy-Owl (Glaucidium gnoma swarthi) in British Columbia''. BC Minist. Sustainable Resour. Manage., Conservation Data Centre, and BC Minist. Water, Land and Air Protection, Biodiversity Branch, Victoria BC. Wildl. Bull. No. B-113. 14pp, 3.</ref> [[ferruginous pygmy owl]] (''Glaucidium brasilianum''),<ref>Proudfoot, G. A. and R. R. Johnson (2000). ''Ferruginous Pygmy-Owl (Glaucidium brasilianum)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> [[burrowing owl]] (''Athene cunicularia''),<ref name= Cartron/> [[boreal owl]] (''Aegolius funereus'')<ref>Hayward, G. D. and P. H. Hayward (1993). ''Boreal Owl (Aegolius funereus)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> and [[northern saw-whet owl]] (''Aegolius acadicus'').<ref name= Reynolds3/> Medium to large-sized owls are sometimes also prey for Cooper's hawks have been known to include [[long-eared owl]] (''Asio otus'') and perhaps the rather large [[spotted owl]] (''Strix occidentalis'').<ref>Bloom, P. H. (1994). ''The biology and current status of the long-eared owl in coastal southern California''. Bulletin of the Southern California Academy of Sciences, 93(1), 1–12.</ref><ref>Bull, E. L., Wright, A. L., & Henjum, M. G. (1989). ''Nesting and diet of Long-eared Owls in conifer forests, Oregon''. The Condor, 91(4), 908–912.</ref><ref>Forsman, E. D., Meslow, E. C., & Wight, H. M. (1984). ''Distribution and biology of the spotted owl in Oregon''. Wildlife Monographs, 3–64.</ref> Most impressively, an instance was observed where a Cooper's hawk appeared to have preyed upon an adult of the rather larger (averaging about {{convert|787|g|lb|abbr=on}}) [[barred owl]] (''Strix varia'').<ref name= Stirling/> There is also a record of a barred owl preying on a Cooper's hawk as well.<ref>Hertzel, A. (2003). ''Barred Owl takes Cooper's Hawk?'' Loon 75: 58.</ref>

==Breeding==
===Breeding territory and prelaying behavior===
[[File:Cooper&#039;s Hawks in love (an older male and young female) (33861751226).jpg|thumb|left|A breeding pair of Cooper's hawks, consisting of an adult male and an immature female.]]
Cooper's hawk is a solitary bird apart from breeding and rare aggregations during migration.<ref name= Ferguson-Lees/> This species usually is considered monogamous.<ref name= Palmer/> However, pairings of two males (1 young, 1 adult) with a single female have been recorded at least three times.<ref>Boal, C. W., & Spaulding, R. L. (2000). ''Helping at a Cooper's Hawk nest''. The Wilson Journal of Ornithology, 112(2), 275–277.</ref><ref>Deal, E., Bettesworth, J., & Muller, M. (2017). ''Two records of female Cooper's Hawks courting two different males in neighboring urban territories''. Journal of Raptor Research, 51(1), 83–84.</ref> In [[Grand Forks, North Dakota]], a single male has been recorded to successfully mate with two nearby females, with similar records from New Mexico. However, the breeding efforts in Grand Forks were found to be disproportionately producing males, seven to one.<ref name=BOW/><ref name= Stout2/><ref>Driscoll, T. G. (2015). ''Polygyny leads to disproportionate recruitment in urban Cooper's Hawks (Accipiter cooperii)''. Journal of Raptor Research, 49(3), 344–346.</ref> A Wisconsin study determined 19.3% of nestlings in a Milwaukee study area were from extra-pair couplings and that 34% of all broods included at least 1 extra-pair young.<ref>Rosenfield, R. N., Sonsthagen, S. A., Stout, W. E., & Talbot, S. L. (2015). ''High frequency of extra‐pair paternity in an urban population of Cooper's Hawks''. Journal of Field Ornithology, 86(2), 144–152.</ref> Despite their generally monogamous breeding system, Cooper's hawks are often rather inconsistent regarding breeding for life (as many other birds of prey do). While males are more or less devoted to same breeding sites throughout lifetime, 23% of adult females in Wisconsin moved to different nesting grounds from {{convert|0.8|to|14.6|km|mi|abbr=on}} away, averaging {{convert|2.6|km|mi|abbr=on}}, in subsequent years.<ref name= Rosenfield4/><ref>Rosenfield, R. N., & Bielefeldt, J. (1996). ''Lifetime nesting area fidelity in male Cooper's Hawks in Wisconsin''. The Condor, 98(1), 165–167.</ref><ref name= SourceorSink>Rosenfield, R. N., Hardin, M. G., Taylor, J., Sobolik, L. E., & Frater, P. N. (2019). ''Nesting Density and Dispersal Movements between Urban and Rural Habitats of Cooper's Hawks (Accipiter cooperii) in Wisconsin: Are These Source or Sink Habitats?'' The American Midland Naturalist, 182(1), 36–51.</ref> Meanwhile, in Arizona, 3% of males and 10% of females displayed yearly breeding dispersal.<ref name= Mannan3>Mannan, R. W., Mannan, R. N., Schmidt, C. A., Estes-Zumpf, W. A., & Boal, C. W. (2007). ''Influence of natal experience on nest‐site selection by urban‐nesting Cooper's hawks''. The Journal of Wildlife Management, 71(1), 64–68.</ref> However, in the urbanized areas of Tucson, evidence indicates that mate fidelity is higher than elsewhere. In Tucson, it was found that the mean distance of the mated pairs was only {{convert|473.4|m|ft|abbr=on}} during the non-breeding season and 36 interactions were recorded almost all in the core range, indicating an unusually close perennial typical pair bond here.<ref>Boggie, M. A., Mannan, R. W., & Wissler, C. (2015). ''Perennial pair bonds in an Accipiter: a behavioral response to an urbanized landscape?'' Journal of Raptor Research, 49(4), 458–470.</ref> The rate of dispersal to a different breeding ground was a much higher at 68% in north Florida.<ref name= Millsap/>

Data in Wisconsin shows that pairs line up in correspondence with their size, i.e. larger female Cooper's hawks mate with large males and smaller females with smaller males. The data indicated that larger pairs tend to have earlier laying dates, larger broods and more recruits than smaller ones. Relatively large body mass may be a heritable trait. However, no correlation was found between the age of the pair and apparent breeding site quality and time of breeding or annual productivity (though older females may lay slightly earlier than yearlings in most cases).<ref name= Rosenfield4/><ref>Rosenfield, R. N., & Bielefeldt, J. (1999). ''Mass, reproductive biology, and nonrandom pairing in Cooper's Hawks''. Auk, 116: 830–835.</ref><ref name= Bozek>Rosenfield, R. N., Bielefeldt, J., Booms, T. L., Cava, J. A., & Bozek, M. A. (2013). ''Life-History Trade-Offs of Breeding in One-Year-Old Male Cooper's Hawks Accipiter cooperii''. The Condor, 115(2), 306–315.</ref> In Arizona, birds of each sex were found to usually pair with like-age individuals.<ref name= Boal4>Boal, C. W. (2001). ''Nonrandom mating and productivity of adult and subadult Cooper's Hawks''. Condor, 103:381–385.</ref> Pairs frequently high circle together.<ref name= Ferguson-Lees/> Either sex or the pair together perform in [[courtship display|courtship]], sometimes over an open field. Courting usually occurs on bright, sunny days, in midmorning.<ref name= Brown/> During sky-dances by males, the wings are raised high over back in a wide arch with slow, rhythmic flapping, similar to the flight of a [[nighthawk]], with exaggerated down strokes. Often, much like the American goshawk, the displaying male flares his undertail coverts.<ref name= Beebe/><ref name= Mockford>Mockford, E. L. (1951). ''Courtship performance of male Cooper's Hawk, Accipiter cooperii''. Indiana Aud. Quart. 29: 58–59.</ref> Sometimes frequently for a month or so, the pair will perform as such.<ref name= Brown/> When perching together, the male usually keeps on a perch at least {{convert|1|m|ft|abbr=on}} away from his unpredictable larger mate.<ref name=BOW/> The bowing display reported in Wisconsin, usually (but not always) done by the male, may be a sign to the other mate of their readiness to nest build.<ref name= Rosenfield7/> Breeding may begin as early as February in the southern part of range, but, for the most part, the breeding season is from April to July.<ref name= Ferguson-Lees/> In central New York, the male arrives in nesting woods by March, initially defending an area of {{convert|100|m|ft|abbr=on}} or so.<ref name= Brown/><ref name= Meng/> Both members of pair arrive by early March in Wisconsin and, in both Pennsylvania and Wisconsin, nest building and copulation is often complete within the month of March.<ref name= Meng/><ref name= Rosenfield6/><ref name= Rosenfield11/> Generally both members of a pair remain on the breeding ground vicinity year-around in Arizona, New Mexico and even in British Columbia.<ref name= Boal4/><ref name=Lien/>

In Michigan, the density average was 1 pair per {{convert|1554|ha|acre|abbr=on}}.<ref name= Craighead/> In North Dakota, 10–12 pairs were found on {{convert|23310|ha|acre|abbr=on}}.<ref>Postovit, H. R. (1979). ''Population estimates of breeding raptors in the North Dakota Badlands'' (Doctoral dissertation, North Dakota State University).</ref> 1 nest per {{convert|734|ha|acre|abbr=on}} in central Wisconsin, 1 nest per {{convert|2321|ha|acre|abbr=on}} in northwestern Oregon and 1 nest per {{convert|2200|ha|acre|abbr=on}} in eastern Oregon.<ref name= Rosenfield8/><ref name= Reynolds6>Reynolds, R. T., & Wight, H. M. (1978). ''Distribution, density, and productivity of accipiter hawks breeding in Oregon''. The Wilson Bulletin, 182–196.</ref> Minimal distance between active nests is seldom less than {{convert|0.7|to|1|km|mi|abbr=on}}.<ref name= Fitch2/><ref name= Fischer/><ref name= Asay>Asay, C. E. (1987). ''Habitat and productivity of Cooper's Hawks nesting in California''. California Fish and Game, 73: 80–87.</ref> Distance between active nest on average was {{convert|1.6|km|mi|abbr=on}} in both California and Arizona, {{convert|2.4|km|mi|abbr=on}} in New York, {{convert|1|km|mi|abbr=on}} in Kansas, {{convert|5|km|mi|abbr=on}} in western Oregon and {{convert|3.5|km|mi|abbr=on}} in eastern Oregon and {{convert|1.6|km|mi|abbr=on}} in central Wisconsin.<ref name= Snyder/><ref name= Meng/><ref name= Fitch/><ref name= Reynolds6/><ref>Brandt, H. (1951). ''Arizona and its bird life'' (The Bird Research Foundation, Cleveland, Ohio).</ref> Mean distance between active nests in Illinois was {{convert|5.3|km|mi|abbr=on}}.<ref name= Kirk>Kirk, D. R., & Waring, G. H. (1997). ''STUDY OF FACTORS AFFECTING REPRODUCTIVE SUCCESS OF COOPER'S HAWKS IN SOUTHERN ILLINOIS''. Illinois Department of Natural Resources Report.</ref> Rather small areas may be defended where hunting occurs near the nest.<ref name= Palmer/> Typical home range sizes for Cooper's hawks are between {{convert|400|and|1800|ha|acre|abbr=on}}.<ref name= Craighead/><ref name= Status>Reynolds, R. T. (1989). ''Status reports: Accipiters''. Paper read at Proc. western raptor management symposium and workshop, at Washington, D.C.</ref> Home range for a Wisconsin male hawk is around {{convert|193|to|571|ha|acre|abbr=on}} during breeding and about {{convert|732|ha|acre|abbr=on}} during non-breeding.<ref name= Murphy/> Exceptionally close active and successful nests were recorded only {{convert|160|m|ft|abbr=on}} apart in [[Albuquerque]] and {{convert|270|m|ft|abbr=on}} in Victoria, British Columbia.<ref name=BOW/><ref name= Rosenfield8/> Male home ranges in Tucson (sample size 9) averaged {{convert|65.5|ha|acre|abbr=on}}, being smaller than in Wisconsin due to better prey concentrations (doves), however juvenile males in rural Tucson areas covered a home range of {{convert|771|ha|acre|abbr=on}}.<ref>Mannan, R. W., & Boal, C. W. (2000). ''Home range characteristics of male Cooper's Hawks in an urban environment''. The Wilson Journal of Ornithology, 112(1), 21–27.</ref><ref name= Matter>Mannan, R. W., Estes, W. A., & Matter, W. J. (2004). ''Movements and survival of fledgling Cooper's Hawks in an urban environment''. Journal of Raptor Research, 38(1), 26–34.</ref> Breeding hawks in [[Oshkosh, Wisconsin]] had an average home range of {{convert|238|ha|acre|abbr=on}}.<ref name= SourceorSink/> In southwest Tennessee, a male Cooper's hawk had a home range size of {{convert|331|ha|acre|abbr=on}} and 4 females had an average range of {{convert|869|ha|acre|abbr=on}}.<ref name= Lake/> Slightly smaller home ranges were found for urban males in a California study, at a mean of {{convert|481|ha|acre|abbr=on}}, than in non-developed areas here, which showed a mean of {{convert|609|ha|acre|abbr=on}}.<ref>Chiang, S. N., Bloom, P. H., Bartuszevige, A. M., & Thomas, S. E. (2012). ''Home range and habitat use of Cooper's Hawks in urban and natural areas''. Urban Bird Ecology and Conservation, 45, 1–16.</ref> Huge male home ranges were found for breeding ones in New Mexico, at {{convert|1206|ha|acre|abbr=on}}, and in north Florida, at {{convert|1460|ha|acre|abbr=on}}, probably due to dispersed prey resources.<ref name= Millsap/><ref>Kennedy, P. L. (1989). ''The nesting ecology of Cooper's Hawks and Northern Goshawks in the Jemez Mountains, NM: a summary of results, 1984–1988 (Final Report)''. Santa Fe National Forest, U.S.D.A. Forest Service.</ref> Home ranges of females tend to constrict with age.<ref name=BOW/> An exceptionally pronounced case of this was in north Florida, where first year female home ranges went from up to about {{convert|932|km2|sqmi|abbr=on}} down to as little as {{convert|4|km2|sqmi|abbr=on}}.<ref name= Millsap/> In central New York, the nest sites of various other woodland birds were surprisingly close to those of Cooper's hawks, though some of the nest were occupied by other birds of prey that are not regularly threatened by these hawks (though flickers, one of the birds most at threat by the hawks, were fairly dispersed away from the hawk's nests).<ref name= Palmer/><ref name= Meng/> As in most accipitrids, copulation is brief (averaging about 4.5 seconds) and frequent (at around 0.9 per hour), with total copulations averaging per season about 372.<ref name=BOW/>

===Nest===
[[File:Accipiter cooperii nest.jpg|thumb|The large, bulky nest of a Cooper's hawk with the female perched on it.]]
This species builds a bulky platform nest, usually {{convert|61|to|76|cm|in|abbr=on}} across and {{convert|15|to|45|cm|in|abbr=on}} deep. Often the nest is shallower in conifers (i.e. {{convert|15|to|20|cm|in|abbr=on}} deep in New York) and deeper in broad-leafed trees (averaging {{convert|43|cm|in|abbr=on}} in New York).<ref name= Ferguson-Lees/><ref name= Meng/> Nests average larger in the eastern part of the range than in the west, perhaps in keeping with the eastern hawks' larger average body sizes.<ref name= Bosakowski2>Bosakowski, T., Smith, D.G. & Speiser, R. (1992). ''Niche overlap of two sympatric-nesting hawks Accipiter spp. in the New Jersey–New York Highlands''. Ecography, 15: 358–372.</ref> While sticks are almost always used, one unusual Florida nest was observed to be made largely of [[Spanish moss]] (''Tillandsia usneoides'').<ref name= Palmer/><ref>Grimes, S. A. (1944). ''Birds of Duval County (continuing)''. Florida Nat, 17, 21–31.</ref> Often nests are lined by Cooper's pair with bark or odd bits of greenery. The male grabs at bark like prey, while the female, if participating, may tear off bark with her bill; the piles of bark may be up to 3 inches deep by the time eggs are laid, though green spray is added considerably less often than other species of hawks such as ''Buteo''.<ref name= Ferguson-Lees/><ref name= Brown/> One male, unusually, was seen to be engaging in nest building while helping parent an active brood in mid-summer.<ref>Rosenfield, R. N., & Sobolik, L. E. (2017). ''Unusual Timing of Alternative Nest Building by an Urban Cooper's Hawk (Accipiter cooperii)''. Journal of Raptor Research, 51(4), 483–484.</ref> Nest are often located at {{convert|8|to|15.1|m|ft|abbr=on}} above the ground in the main fork or horizontal branch close to the trunk, though are sometimes up to {{convert|20|m|ft|abbr=on}} above the ground, and in trees usually of {{convert|21|to|52|cm|in|abbr=on}} in diameter.<ref name= Ferguson-Lees/><ref name=BOW/><ref name= Reynolds2/><ref name= Titus/><ref name= Wiggers/><ref name= Asay/><ref name= Moore>Moore, K. R. & Henny, C.J. (1984). ''Age-specific productivity and nest site characteristics of Cooper's Hawks (Accipiter cooperii)''. Northwest Science, 58: 290–299.</ref><ref name= NM>Kennedy, P. L. (1988). ''Habitat characteristics of Cooper's Hawks and Northern Goshawks nesting in New Mexico''. In Proceedings of the Southwestern Raptor Management Symposium and Workshop (R. Glinski, B. G. Pendleton, M. B. Moss, B. A. Millsap, and S. W. Hoffman, Editors). National Wildlife Federation, Washington, DC, USA. pp. 218–227.</ref> Usually nest sites are within plots of woodland of at least {{convert|4|to|8|ha|acre|abbr=on}} in size, with a canopy coverage usually over 64%, but can be much smaller in some urban vicinities.<ref name= Rosenfield8/><ref name= Mannan/><ref>Price, H. F. (1941). ''Nests and eggs of the Cooper's Hawk''. Oologist, 58:26–27.</ref><ref>Call, M. (1978). ''Nesting habitats and surveying techniques for common western raptors''. U.S. Bureau of Land Management, Denver, CO, USA.</ref><ref>Stewart, R. E. (1975). ''Breeding Birds of North Dakota''. Tri-College Center for Environmental Studies, Fargo, ND, USA.</ref> One unusual nest in North Dakota was in dense shrub rather than a tree and it even successfully produced fledglings.<ref>Sondreal, M. & Murphy, R.K. (1998). ''Low Cooper's Hawk, Accipiter cooperii, nest in dense shrubs''. Canadian Field-Naturalist, 112: 339–340.</ref> Another unconventional nesting area in North Dakota in the [[Little Missouri National Grassland]] and was recorded to have unusually open canopy, at a mean of 55%, and to be in a rather steep sloped area.<ref>Rosenfield, R. N., Bielefeldt, J., Rosenfield, L. J., Murphy, R. K., Bozek, M. A., & Grosshuesch, D. A. (2002). ''The status of Merlin and Cooper's Hawk populations on the Little Missouri National Grassland in western North Dakota''. Report to US Department of Agriculture, Forest Service, Minot, ND.</ref> An unusual nest site in Wisconsin was on a [[grapevine]].<ref>Hamerstrom, F. (1972). ''Birds of prey of Wisconsin''. Department of Natural Resources.</ref> Water access is of secondary import.<ref name= Hennessy/><ref name= Millsap/><ref name= Titus/> Pine plantations are popular nesting sites across several parts of the range.<ref name= Rosenfield6/><ref name= Wiggers/> In Tucson, 70.8% of 48 nests were found to be non-native ''[[Eucalyptus]]'' trees.<ref>Boal, C. W., Mannan, R.W. & Hudelson, K.S. (1998). ''Trichomoniasis in Cooper's Hawks from Arizona''. Journal of Wildlife Diseases 34:590–593.</ref> Native [[Pinus strobus|white pine]] (''Pinus strobus'') was preferred in [[Massachusetts]], at 58% of 48 nests, and in Pennsylvania, at 78% of 18 studied nests, and the most used tree in a study from Wisconsin as well, at 35% of 82 nests.<ref name= Palmer/><ref name= Bent/><ref name= McConnell>McConnell, S. (2003). ''Nest site vegetation characteristics of Cooper's Hawks in Pennsylvania''. Journal of the Pennsylvania Academy of Science. 76 (2–3): 72–76.</ref> [[Pinus echinata|Shortleaf pine]] (''Pinus echinata''), another native was preferred in Missouri (at 51% of 43 nests) and in Illinois (at 81% of 16 nests).<ref name= Wiggers/><ref>Ehrlich, R. M. & Drickamer, L.C. (1993). ''Habitats used for nesting by Cooper's Hawks (Accipiter cooperii) in southern Illinois''. Transactions of the Illinois State Academy of Science, 86: 51–62.</ref> Deciduous trees may be preferred elsewhere in the east, such as [[Fagus grandifolia|American beech]] (''Fagus grandifolia'') in New York (39% of 36 nests), [[oak]]s in Maryland (66%) and [[Quercus laurifolia|laurel oak]] (''Quercus laurifolia'') in north Florida (81% of 77 nests).<ref name= Meng/><ref name= Millsap/><ref name= Janik/> [[Douglas fir]]s (''Pseudotsuga menziesii'') were preferred in northwest Oregon (94% of 18 nests) and also in northeast Oregon as well as in British Columbia (34% of 64 nests), often where [[mistletoe]] parasitizes the tree (64% of 31 in the overall state of Oregon were on mistletoe).<ref name= Reynolds/><ref name= Moore/><ref name= Moore2>Moore, K. R., & Henny, C. J. (1983). ''Nest site characteristics of three coexisting accipiter hawks in northeastern Oregon''. Raptor Research, 17(3), 65–76.</ref><ref>Campbell, R. W., Dawe, N.K. McTaggart-Cowan, I., Cooper, J.M. Kaiser, G.W. & McNall, M.C.E. (1990). ''The Birds of British Columbia, Volume 2''. Diurnal Birds of Prey Through Woodpeckers. Royal British Columbia Museum, Victoria, BC, Canada.</ref> [[Pinus ponderosa|Ponderosa pine]] (''Pinus ponderosa'') were preferred in eastern Oregon (53% of 15 nests) as well as in New Mexico.<ref name= Reynolds/><ref name= NM/><ref>Siders, M. S. & Kennedy, P.L. (1996). ''Forest structural characteristics of accipiter nesting habitat: Is there an allometric relationship?'' Condor, 98:123–132.</ref> In the enormous [[Sequoioideae|redwood forests]] of California, all Cooper's hawk nests were in more modestly sized native [[Notholithocarpus|tan-oaks]] (''Notholithocarpus densiflorus'').<ref>Douglas, R. B., Nickerson, J., Webb, A. S., & Billig, S. C.  (2000). ''Landscape and Site-Level Habitat Characteristics Surrounding Accipiter Nests on Managed Timberlands in the Central Coast Redwood Region''. In ''Region Forest Science Symposium: What Does the Future Hold?'' (p. 499).</ref>

It has historically taken to almost be a rule that Cooper's hawk uses a new nest site each year.<ref name= Brown/><ref name= Meng/><ref name= Fitch2/><ref name= Moore/><ref>Schriver, E. C., Jr. (1969). ''The status of Cooper's Hawks in western Pennsylvania''. In ''Peregrine Falcon Populations: Their Biology and Decline'' (J. J. Hickey, Editor). University of Wisconsin Press, Madison, WI, USA. pp. 356–359.</ref> Exceptionally, though, pairs have used the same nests for up to 4 years, though mostly records show up to 2 to 3 years of use when a nest is reused.<ref name= Brown/><ref name= Moore/> As much as 59% of 17 nests (New Mexico) or 66.7% of 12 nests (southern Illinois) may be reused in the following year but this is not usual.<ref name= Moore/><ref name= Kirk/> In north Florida, 21% of nests were reused in a subsequent year, while in New York, it was around 10%.<ref name= Meng/><ref name= Millsap/> New nests are often near prior nests, at a mean distance between them of around {{convert|170|m|ft|abbr=on}} in Wisconsin.<ref name= Rosenfield11/> In Alberta, a female was reported to use a grove of trees over two consecutive years as a nest site, be absent for one year and then returned to nest in the same grove the subsequent year.<ref>Hohn, E.O. (1983). ''The Northern Naturalist''. Lone Pine Media Productions Ltd., Edmonton, Alberta.</ref> Nest building usually takes about two weeks.<ref name= Palmer/><ref name=BOW/> However, if a clutch is lost, a pair may repair and use another nest within four days.<ref name= Brown/> A majority of 385 nests (40–60% annually) in Wisconsin built on pre-existing structures.<ref name= Rosenfield8/> At times, the material is put on the residue of a crow's nest, squirrel's [[drey]] or even a [[Pack rat|woodrat]] tree nest.<ref name= Brown/><ref name= Fitch/> In Tucson, nest building was recorded during winter, exceptionally.<ref>Boal, C. W., Bibles, B. D., & Mannan, R. W. (1997). ''Nest defense and mobbing behavior of Elf Owls''. Journal of Raptor Research, 31(3), 286–287.</ref> When grass is found to be incorporated in nest structure, it is an indication that Cooper's is using a nest built by crows as they have never themselves been known to use grass.<ref name= Palmer/> Oregon nests frequently incorporate [[mistletoe]] into the nest, more so those built by pairs with mature females rather than juvenile females.<ref name=BOW/> Their nest structure requires about 4.8 support branches.<ref name=BOW/> Data is conflicting on whether it is the male or the female who selects the nest site.<ref name= Meng/><ref name= Moore/> Males were found to do 70% of the nest building in Wisconsin but the female does not consistently take a secondary role. Mostly, the male gathers nesting materials within {{convert|100|to|200|m|ft|abbr=on}} of the nest.<ref name= Rosenfield6/> The male snaps off twigs with his feet to build with, though smaller twigs may be carried in the bill. After an early duet, at as early as 5:30, the male may start nest building at around 6:30. Later in the day, he will hunt, though females also hunt at this stage, much of her food is brought by him.<ref name= Brown/> South-facing nests are thought to be avoided, possibly due to [[solar irradiance]] reducing soil moisture, tree density and shading or possibly due to the more deciduous local nature of north-facing nest sites.<ref name= Reynolds/><ref name= Bosakowski/> When using a prior years nest, the female reportedly selects and repairs it.<ref name= Brown/>

===Eggs ===
[[File:Illustrations of the nests and eggs of birds of Ohio (Pl. XLIX) (6058397501).jpg|thumb|The second row shows the unmarked eggs of Cooper's hawks, compared to those of [[American kestrel]]s (line 1), [[red-shouldered hawk]]s (line 3) and [[red-tailed hawk]]s (line 4).]]
Egg laying in New York is between after April 24 to June 26 (about 50% from May 10 to 20) with similar dates in New England and also from Ohio to Minnesota.<ref name= Palmer/><ref name=BOW/><ref>Rodewald, P. G., Shumar, M. B., Boone, A. T., Slager, D. L., & McCormac, J. (Eds.). (2016). ''The second atlas of breeding birds in Ohio''. Pennsylvania State University Press.</ref> Similar laying dates were also found for Ontario as well as in British Columbia, but more laying date variation was found for the latter province.<ref name=BOW/><ref name= Peck>Peck, G.K., & James, R.D. (1983). ''Breeding Birds of Ontario: Nidiology and Distribution Volume 1: Nonpasserines''. Royal Ontario Museum, Toronto, Ontario, Canada.</ref> Data shows that mean egg laying times in Wisconsin may be shifting earlier by up to 4–5 days in different years, but the current mean is 1.3 days.<ref name= Snowstorm/><ref>Rosenfield, R. N., Hardin, M. G., Bielefeldt, J., & Keyel, E. R. (2017). ''Are life history events of a northern breeding population of Cooper's Hawks influenced by changing climate?'' Ecology and evolution, 7(1), 399–408.</ref> Similar shifts may be occurring in New York state as well.<ref name= Meng/><ref>McGowan, K. J., & Corwin, K. (2008). ''The Second Atlas of Breeding Birds in New York State''. Cornell University Press, Ithaca, NY, USA.</ref> From New Jersey to Virginia, egg laying may be from April 7 to May 23 (about 52% from April 29 to May 11), with similar dates on the opposite coast, from Washington state to California.<ref name= Palmer/><ref name= Asay/> From Florida to Baja California, egg-laying can began as early February, but, despite the lower latitude, known records show most are between mid-April and early May and can even run into June.<ref name= Palmer/><ref name= Layne/> Similar egg-laying dates, peaking around late April, are known in Arizona.<ref name= Millsap2>Millsap, B. A. (1981). ''Distributional Status of Falconiformes in West Central Arizona with Notes on Ecology, Reproductive Success, and Management''. U.S. Bureau of Land Management Technical Note 355.</ref> The mean clutch initiation, in 57 clutches from North Dakota was mid-May and, though pairs arrive more than a month before that, the mean dates are consistently 2–3 weeks later in nests at other similar latitude in British Columbia and Wisconsin.<ref name= Nenneman>Nenneman, M.P., Murphy, R.K. & Grant, T.A. (2002). ''Cooper's Hawks, Accipiter cooperii, successfully nest at high densities in the northern Great Plains''. Canadian Field-Naturalist 116:580–584.</ref> It was determined in Maryland that egg-laying and other mean dates rival or are even later than the longer distance migrating broad-winged hawk, and are much later in general than other ''Buteo'' hawks here.<ref name= Janik/> Dates of egg laying and other behaviors were also found to average slightly later than the even further migrating ''Buteo'', the [[Swainson's hawk]] (''Buteo swainsonii'').<ref>Murphy, R. K., & Ensign, J. T. (1996). ''Raptor nesting chronology in northwestern North Dakota''. US Fish & Wildlife Publications, 62.</ref> The clutch size averages anywhere from about three to five.<ref name= Ferguson-Lees/> Female egg laying is individually consistent from year-to-year, with a variance of a day or two. Often about 3–5 eggs are laid every other day, though can be up to 2 days between the 4th and 5th eggs.<ref name= Brown/>

Clutch sizes fell historically from a mean of 3.5 (1929–1945) to 3.1 (1946–1948) and 2.7 (1949–1967) during the use of [[DDT]] then back up to 3.3 in 1967–1976 after DDT was banned.<ref name= Henny3>Henny, C. J., & Wight, H. M. (1972). ''Population ecology and environmental pollution: Red-tailed and Cooper's hawks''. In ''Population ecology of migratory birds: a symposium''. US Fish and Wildlife Service, US Department of Interior, Washington, DC, USA (pp. 229–250).</ref><ref>Braun, C. E., Enderson, J. H., Henny, C. J., Meng, H., & Nye Jr, A. G. (1977). ''Conservation committee report. Falconry: Effects on raptor populations and management in North America''. The Wilson Bulletin, 89(2), 360–369.</ref> 7 of 266 clutches in early museum records were 6 egg clutches while one 7 egg clutch was recorded in Arizona.<ref name= Bent/><ref>Ellis, D. H., & Depner, G. (1979). ''A Seven-Egg Clutch for the Cooper's Hawk''. The Condor, 81(2), 219–220.</ref> Records of 2 egg clutches may usually be laid by yearling females.<ref name= Palmer/> The mean clutch size in 72 clutches was 3.5 and 3.33 in 46 clutches in central Arizona.<ref name= Palmer/><ref>Apfelbaum, S. I., & Seelbach, P. (1983). ''Nest tree, habitat selection and productivity in seven North American raptors''. J. Raptor Res, 17, 99–104.</ref> Clutch sizes were similar in Ontario, at around a mean of 3.4, and in North Dakota, at 3.5.<ref name= Peck/><ref name= Indices>Rosenfield, R. N., Bielefeldt, J., Rosenfield, L. J., Stewart, A. C., Nenneman, M. P., Murphy, R. K., & Bozek, M. A. (2007). ''Variation in reproductive indices in three populations of Cooper's Hawks''. The Wilson Journal of Ornithology, 119(2), 181–188.</ref> In southern Illinois, the mean clutch size is 4.1.<ref name= Kirk/> The average clutch size in Wisconsin Cooper's hawks was 4.3, with a little varying range of 3.9 to 4.8 over 6 years. The clutch size in Wisconsin is on average 1–3 eggs smaller in immature females.<ref name= Bozek/> There was no strong differences in Wisconsin in clutch sizes between urban and rural locations.<ref name= Rosenfield8/><ref>Rosenfield, R. N. (1996). ''Urban nesting biology of Cooper's Hawks in Wisconsin''. Raptors in human landscape, 41–44.</ref> In British Columbia, the mean clutch size was a particularly high 4.43.<ref name= Indices/> A clutch of 5 may be laid in 10 days and hatch in a span of about 3 days.<ref name= Palmer/> Some authors suspect that clutch size is functionally reliant on habitat quality.<ref name= Snyder/> The eggs are pale sky blue, fading to dirty white, with a smooth texture. However, an occasional set is reported as lightly spotted. It is reported by some authorities that the spotted eggs are laid by a female that does so each year, however others opine that these are misidentified eggs that were laid by broad-winged hawks.<ref name= Palmer/><ref name= Brown/> The eggs may measure {{convert|43|to|54|mm|in|abbr=on}} in height by {{convert|34|to|42|mm|in|abbr=on}} by diameter (averaging {{convert|47|to|49.1|x|37.6|to|38.7|mm|in|abbr=on}} in 121 from Ohio and 137 from New York, respectively).<ref name= Palmer/><ref name= Brown/><ref name= Meng/> California eggs averaged {{convert|47.5|x|37.6|mm|in|abbr=on}} in a count of 82.<ref name= Asay/> The average weight of eggs is {{convert|43|g|oz|abbr=on}} (with a range of {{convert|36|to|52|g|oz|abbr=on}}).<ref name= Palmer/>

===Parental behavior===
Incubation starts with the laying of the third egg.<ref name= Palmer/> Evidence shows that pairs may be able to successfully delay breeding somewhat if it is unusually harsh and snowy early spring.<ref name= Snowstorm/> The female mainly incubates (including throughout nighttime) though the male may substitute for 10–30 minutes after he brings his mate food, often doing so for about 2 to 3 times a day.<ref name= Meng/> The male usually roosts nearby during incubation, when he begins calling, she may join for 5–10 minutes before quickly flying back.<ref name= Palmer/> By the third week, she may leave the nest only to take food or to defecate. Incubation lasts for 34–36 days, but sometimes may be down to 30 days.<ref name= Palmer/><ref name=BOW/> Eggs may be discarded by the mother after hatching but those that never hatch are left in place. The female sleeps on the nest until the young are 2 weeks old. The young were photographed to sleep at night directly under her body until there is not enough room to do so.<ref name= Brown/> The male is rarely present at nest longer than 3–4 seconds after hatching but at least once was recorded staying for 3 minutes when coming with prey after the female stops heavily brooding. Most prey deliveries are intercepted by the female slightly away from the nest.<ref name= Palmer/> However, often the male does not perch far away, averaging about {{convert|765|m|ft|abbr=on}}, away from the nest during nesting to fledging stages, and occasionally as close as {{convert|120|m|ft|abbr=on}}.<ref name= Murphy/> The nest may be crowded while the nestlings grow, and the female may expand platform with additional sticks.<ref name= Brown/> Usually the male Cooper's hawk removes the head and viscera of prey before bringing it, then taking it to plucking stumps, although often the plucking is done right where prey is killed.<ref name= Brown/> Rate of feeding depends on brood size but is dictated in part by the availability and size of prey.<ref name= Kennedy/><ref>Snyder, N. F., & Snyder, H. A. (1973). ''Experimental study of feeding rates of nesting Cooper's Hawks''. Condor, 461–463.</ref> Only 2 to 3 food deliveries daily are usually necessary during incubation but the male has to hunt constantly once the young are large, rarely plucking and no longer decapitating prey.<ref name= Brown/> Peak deliveries are typically needed in about the 4th week.<ref name= Meng2/><ref name= Murphy/> 6–9 deliveries a day are usually necessary for broods of 3 to 5.<ref name=BOW/> New Mexican nests with adult females had 95 prey deliveries in 120 hours of observations, whereas nest with younger females (i.e. second years), there were 65 prey deliveries were observed in 120 hours, or 694 fewer prey individuals per square kilometer than nests on territories of adult females.<ref name= Lien/> The parents are non-aggressive usually when the nest area is breached but the female may dive and call if a person climbs directly to their nest, sometimes also the male, often doing so silently.<ref name= Palmer/> The reaction to human intrusion varies among individuals and probably with stage of nesting, hatch date, and probably prior experience. Generally, individuals rarely strike humans.<ref name= Meng/><ref name= investment>Rosenfield, R.N. & Bielefeldt, J. (1991). ''Reproductive investment and anti-predator behavior in Cooper's Hawks during the pre-laying period''. J. Raptor Res, 25(4), 113–115.</ref> Prolonged visits to the nest by humans, i.e. more than 30 minutes or around an hour, can cause temporary nest abandonment, and can be the cause of up to 1.2% of nest failures.<ref>Rosenfield, R. N., Grier, J.W. & Fyfe, R.W. (2007). ''Reducing management and research disturbance''. In Raptor research and management techniques (D. M. Bird and K. L. Bildstein, Editors), Hancock House, Blaine, WA, USA. pp. 351–364.</ref> During early incubation, the female often quietly flushes if a person comes up to nest tree or knocks on it but will sometimes call if someone climbs to the nest. After 2 weeks, she may begin to make "half-hearted" dives at the climber. After 3 or 4 weeks, some females still quietly flush but others grow increasingly aggressive with much variance in temperament. The aggressiveness increases around hatching, decreases for the first couple weeks after hatching, then quickly increases after 3 weeks. All dives at climbers are mock ones to early on but after the young are about 3 weeks old, either one of the pair may actually hit and draw blood from the climbers. Despite a reputation as a "somewhat aggressive" or even as being a hawk with a "very aggressive defense" towards humans in nest defense, the actual rate of attacks even at peak times seems to be very low and the reputation is thought to be fairly unearned.<ref name= Madden>Madden, K. K. (2011). ''Factors Influencing Nest Site Defense Toward Humans by Cooper's Hawks (Accipiter cooperii) in the Albuquerque Area''. Prescott College.</ref><ref name= Morrison>Morrison, J. L., Terry, M., & Kennedy, P. L. (2006). ''Potential factors influencing nest defense in diurnal North American raptors''. Journal of Raptor Research, 40(2), 98–110.</ref> Various researchers consider this species less aggressive to intruders than sharp-shinned hawks and goshawks, and some even less so than red-shouldered hawks as well.<ref name= Bent/><ref name= Meng/><ref name= Madden/> Anti-predator behavior by parent Cooper's hawks against crows, red-tailed hawks and eastern gray squirrels were observed in Wisconsin to be surprisingly six times more often carried out by the male rather than the female.<ref name= investment/> Female defensive attacks are sufficiently forceful enough to drive away more formidable predators such as [[bobcat]]s (''Lynx rufus'') from the nest area.<ref name= Snyder/> When large quadrupeds walk under the nest, the female may utter a semi-alarm call but does not leave the nest.<ref name= Meng/>

===Development of young===
[[File:HAWK, COOPER&#039;S (7-14-11) juv at nest, patagonia-sonoita creek preserve, scc, az -01 (5937524527).jpg|thumb|left|A large nestling Cooper's hawk peers out of the nest]]

Sex ratio can skew towards male in eggs, nestlings and fledglings in about 54–60% in nests of Cooper's hawks in the region of Milwaukee. However the sex ratio corrected over time in the urban area to an even amount, though it is still skewed outside the city (skewed broods towards males occur in cases where the females may become too costly to bring up, needing longer development stages and more foods).<ref name= Rosenfield8/><ref>Rosenfield, R. N., Bielefeldt, J., & Vos, S. M. (1996). ''Skewed sex ratios in Cooper's Hawk offspring''. The Auk, 957–960.</ref><ref>Rosenfield, R. N., Stout, W. E., Giovanni, M. D., Levine, N. H., Cava, J. A., Hardin, M. G., & Haynes, T. G. (2015). ''Does breeding population trajectory and age of nesting females influence disparate nestling sex ratios in two populations of Cooper's hawks?'' Ecology and evolution, 5(18), 4037–4048.</ref> There are similar cases of male skewed ratios recorded now in southwestern cities (i.e. Tucson and Albuquerque).<ref>Millsap, B. A. (2018). ''Demography and metapopulation dynamics of an urban Cooper's Hawk subpopulation''. Condor, 120: 63–80.</ref><ref name= Mannan2>Mannan, R. W., Steidl, R. J., & Boal, C. W. (2008). ''Identifying habitat sinks: a case study of Cooper's hawks in an urban environment''. Urban Ecosystems, 11(2), 141–148.</ref> Due to the female usually only beginning incubation with the third egg, the first three eggs often hatch on the same day, while the fourth and fifth eggs often hatch one (rarely up to three) day later.<ref name=BOW/> New hatchling young average about {{convert|28|g|oz|abbr=on}} in body mass and are about {{convert|9|cm|in|abbr=on}} in total length.<ref name= Palmer/> Hatchlings are covered in white natal down with blue-gray eyes and are tan to pink on many of the bareparts.<ref name=BOW/> While growth is slow for about three days, sexual dimorphism by size may begin by to be measurable by about seven days of age.<ref name=BOW/> At about 10 days, the nestlings begin to engage in rather feeble standing and wing flapping.<ref name= Palmer/> The bill (at around 11 days) grows about twice as fast as the tarsus (at around 22 days).<ref name=BOW/> At 13 days, the nestlings stretch their legs and often yawn, and at 16 days can be aggressive if the nest is breached by people.<ref name= Brown/> Down first becomes deep and fluffy around two weeks, the following week first feathers among dense down, feather production accelerates but growth slows in the fourth week after which both increase for the fifth week.<ref name= Brown/> By 16–18 days, the nestlings preen well, starts to rip at prey and flap well. Within first two weeks, the young Cooper's hawks begin to defecate over nest edge but often soil the edge of nest.<ref name=BOW/> At three weeks often begin to stand up and feed by themselves and often begin to mantle prey away from each other.<ref name= Palmer/> The young grow is rapid for the period when they are 17 days old to about 23 days, growth then slows down abruptly before they nearly pause growth to feather out and then thereafter become fully grown.<ref name=BOW/> At the age of three weeks a female nestling may stand and be able to fully feed herself.<ref name= Brown/> Sometimes smaller, more agile male nest mates may snatch several bits of meat from their larger sister as if taking food from the mother.<ref name= Brown/> [[Siblicide]] rarely has been proven for this species, and may occur "accidentally" at times. Sometimes a younger sibling that has died from other means may be eaten by the siblings or by the parents.<ref name= Palmer/> In one case, an entire brood of 4 nestlings from 2.5 to 3.5 weeks old were found dead in the nest, apparently having died due to exposure after consistent heavy rains.<ref name= Palmer/> Normal departure from nest is 30 days (up to 27 days) for males and 34 days for females, but averaged sooner in Oregon, at 27–30 days.<ref name= Palmer/><ref name= Brown/> Response to the parents after the young Cooper's becoming branchers depends on their hunger levels. Snyder and Wiley recorded feeding rates of 0.267 per hour for a brood of 2 and 0.564 per hour for a brood of 4. In New York and Wisconsin, the sex ratio of broods roughly even, but slightly male biased in Wisconsin (53.5% or 137 against 119).<ref name= Palmer/> Food may be brought to the nest for the first ten days after the young leave it, as the young often return to rest on it or even to sun from it. Largely, the young are quiet until they leave the nest when they begin their loud, persistent hunger calls.<ref name= Palmer/> Around this stage, the young hawks will frequently engage in play with sticks and pinecones.<ref>Madden, K., Tillinghast, T., & Millsap, B. (2018). ''A photographic guide for aging nestling Cooper's Hawks''. USDI Fish and Wildlife Service, Albuquerque, NM, USA.</ref> After they are about eight weeks old, they may start to hunt for themselves, but are usually still reliant on parents for food.<ref name= Palmer/> The young Cooper's hawks are frequently loud, voracious and aggressive in procuring food from the parents.<ref name=Nicewander/> The parents soon seem to lose interest in feeding the young.<ref name= Brown/> Fledgling occurs at 27–34 days (males averaging earlier), but the young may often returns to nest and are not fully feathered until about 50–54 days.<ref name= Ferguson-Lees/><ref name=BOW/> The siblings often stay within {{convert|4|m|ft|abbr=on}} of each other even after leaving their parents range.<ref name= Sobolik/><ref name= Nicewander/> Siblings before long-distance dispersal may hunt together, although may too steal prey from one another.<ref name= Meng/><ref name= Rosenfield8/><ref>Plunkett, A. M. (1986). ''An experience with Cooper's Hawks''. Loon, 58: 55–60.</ref>

Juveniles Cooper's hawks in mostly urban areas of Arizona wandered somewhat randomly it seems until they were about 2.5–3 months old, when they settled on a wintering ground, averaging {{convert|9.7|km|mi|abbr=on}} for females and averaging {{convert|7.4|km|mi|abbr=on}} in males away from their respective natal sites.<ref name= Mannan3/><ref name= Matter/> From their initial natal site to the site where they ultimately breed, in Wisconsin the average young male Cooper's hawk settled {{convert|7.2|km|mi|abbr=on}} away from their nest of origin and the average young female {{convert|27.6|km|mi|abbr=on}} away.<ref name= Inbreeding>Rosenfield, R. N., & Bielefeldt, J. (1992). ''Natal dispersal and inbreeding in the Cooper's Hawk''. The Wilson Bulletin, 104(1), 182–184.</ref> Attempts to average mean dispersal distances within another study found farther than expected dispersal distances for Cooper's hawks from across the range. These were estimated at {{convert|43|km|mi|abbr=on}}.<ref>Briggs, C. W., Hull, A. C., Hull, J. M., Harley, J. A., Bloom, P. H., Rosenfield, R. N., & Fish, A. M. (2020). ''Natal Dispersal Distance and Population Origins of Migrant Red-Tailed Hawks and Cooper's Hawks''. Journal of Raptor Research, 54(1), 47–56.</ref> Greater dispersal distances by female juveniles are probably meant to limit the likelihood of inbreeding.<ref name=BOW/> In one instance, a grandson Cooper's mated with his grandmother over 3 years while there were two instances known of full siblings mating in Victoria, British Columbia.<ref name= Inbreeding/><ref>Stewart, A. C., Rosenfield, R.N. & Nyhof, M.A. (2007). ''Close inbreeding and related observations in Cooper's Hawks''. Journal of Raptor Research, 41: 227–230.</ref> Cooper's hawks usually first breed at 2 years old but yearlings can often be reported to average at 6 to 22% of the breeding populations in short 3–6-year studies.<ref name= Meng/><ref name= Reynolds6/><ref name= Boal4/><ref name= Moore/><ref name= Hennessy/> Longer-term studies of 16–25 years of large urban populations within Milwaukee, Wisconsin, Tucson, Arizona and Victoria, British Columbia, show yearling females average 16–25% of the breeding population but that breeding by yearling male was uncommon to non-existent.<ref name=BOW/><ref name= Rosenfield8/><ref name= Reynolds6/><ref name= Asay/><ref name= Millsap2/><ref name= Hennessy/> Similarly, 79% more females bred in their first year in study in New Mexico than did males.<ref name= Millsap4>Millsap, B. A., Madden, K., Murphy, R. K., Brennan, M., Pagel, J. E., Campbell, D., & Roemer, G. W. (2019). ''Demographic consequences of sexual differences in age at first breeding in Cooper's Hawks (Accipiter cooperii)''. The Auk, 136(3).</ref> Despite the considerable number of breeding young females, in Oregon, they averaged about 1 egg smaller and nearly a fledgling smaller than their older female counterparts; while results in Albuquerque were even more skewed towards breeding success for older females.<ref name= Moore/><ref name= Lien/> Many studies found no yearling males to be breeding with various populations but 7% of 184 males in Tucson were yearlings over several years of study (78% of which were paired with immature females).<ref name= Boal4/> Only one breeding male in both Victoria, British Columbia (579 sample size) and in Albuquerque (sample size 305) were yearling while 4.8% of 123 in Milwaukee were yearlings (92% of which were paired with an adult female).<ref name= Recruitment/><ref name= Rosenfield8/><ref name= Stout2/><ref name= Bozek/> In New Mexico, males sometimes bred in their first year where there were rich prey concentrations, but had 37% higher mean annual mortality than those who did not breed until mature plumaged. New Mexican data showed that 14% of 20 males bred in their first year and 71% in their second year while 93% of the local female bred in their first year.<ref name= Millsap4/> In addition to Tucson, other cases of successful breeding by pairs of immatures reported in varied areas such as Indiana and New York.<ref>Dancey, H. (1993). ''A pair of subadult Cooper's Hawks nest in Indiana''. Indiana Quarterly 71:26–34.</ref><ref>Rothstein, P. (1993). ''Cooper's Hawk nesting in a suburban garden''. Kingbird 43:278–292.</ref> Considerable numbers of juvenile Cooper's hawks breeding may be historically associated with high turnover within populations.<ref name= Moore/><ref name= Hennessy/> Evidence from the Milwaukee area shows a significant reduction in more recent decades of two-year old or younger breeding hawks, which was indicative of a recovering population.<ref name= Stout3/>

===Breeding success===
[[File:Hawks in Senate Park (43070048134).jpg|thumb|right|Juvenile sibling Cooper's hawks are loosely social shortly after dispersal]]
The average of 117 successful laid clutches was 4.18 eggs laid, 3.53 nestlings in successfully hatched clutches and 3.08 young in 26 successfully fledged broods in the Northeastern United States and [[Eastern Canada|southeastern Canada]].<ref name= Palmer/> Nesting success in western Pennsylvania in 32 successful nests was 3.2 fledglings; in 6 nests within Michigan, a mean of 3 in all nests got to fledge (4.3 eggs, 3 hatchlings on average); in Wisconsin, 3.5 fledglings were produced from successful nests (68.6% of 83 nests produced at least 1 fledgling); a mean of 2 fledged from 11 nests in Maryland and 2.23 fledglings per 41 successful nests in Arizona.<ref name= Palmer/><ref name= Janik/> In Illinois, in all breeding attempts (not just successful ones), the mean number of fledglings was 2.8.<ref name= Kirk/> 81% of New York nests produced fledged young and 75% did so in Pennsylvania.<ref name= Palmer/><ref name= Meng/><ref name= Reynolds/> Nesting success rates in western wildland areas may be lower such as in Utah, where 53.5% of nests fledged young, with many of the failures attributable to owl predation.<ref name= Hennessy/> Data from Oregon showed that 74% hatched and 61.4–69% successfully fledged, a much lower rate of nest success than goshawks, at 90.4%, and, surprisingly, than sharp-shinned hawks, at 91.7%. However, in the Oregon data, the number of eggs hatched was higher in Cooper's at 74% than in sharp-shinned hawks, at 69.4% (but not than the goshawk's).<ref name= Reynolds/><ref>Reynolds, R. T. (1974). ''Distribution, density, and productivity of three species of accipiter hawks in Oregon''.</ref> In Wisconsin in 2019, all of the eggs in a clutch of seven hatched and all of the young fledged.<ref>{{cite journal |last1=Rosenfield |first1=Robert N. |last2=Sonsthagen |first2=Sarah A. |last3=Riddle-Berntsen |first3=Ann |last4=Kuhel |first4=Evan |date=2020 |title=Record fledging count from a seven-egg clutch in Cooper's Hawk (''Accipiter cooperii'') |journal=The Wilson Journal of Ornithology |volume=132 |issue=2 |pages=460–463 |doi=10.1676/1559-4491-132.2.460 }}</ref> In [[North Dakota]], better habitat such as upland forest showed much higher breeding success levels (at least 1 fledgling in 86% of 26 nests) than in poorer habitats such as narrow riparian strips, in which 1 fledgling was produced in 57% of 44 nests.<ref name= Nenneman/> Younger forest in North Dakota was surprisingly preferred, with the average estimated age of trees used by Cooper's at 59.9 against a random tree age in the area of 74.6.<ref>Nenneman, M., Grant, T.A., Sondreal, M.L. & Murphy, R. (2003). ''Nesting habitat of Cooper's Hawks in northern Great Plains Woodlands''. Journal of Raptor Research. 37. 246–252.</ref> It was found that adult female who mated with males who provisioned food at a higher rate produced 1.6 more fledglings on average.<ref name= Lien/> Yearling females in northeastern Oregon tended to use younger successional stands than older females and tended to have lower productivity in clutch size and brood counts.<ref name= Moore/> Among 70 studied male hawks in Wisconsin, the number of fledged young produced in their lifetime was similar in males who did not breed until they were two years old (mean of 8.8 fledglings) compared to those who started breeding as yearlings (mean of 8.7 fledglings), with the most successful studied male having started breeding in his second year and had produced 32 fledglings by the time he was nine years of age.<ref>Rosenfield, R. N., Bielefeldt, J., Rosenfield, L. J., Booms, T. L., & Bozek, M. A. (2009). ''Survival rates and lifetime reproduction of breeding male Cooper's Hawks in Wisconsin, 1980–2005''. The Wilson Journal of Ornithology, 121(3), 610–617.</ref> In Arizona and New Mexico, 23% of nests failed altogether and 56.5% of 23 nests in Wisconsin failed during incubation.<ref name= Palmer/><ref name= Snyder/> A high genetic diversity, or [[allele]] level, was found in the nestlings of the urbanized population of Tucson, ensuring a hardy local population despite historic concerns about the parasite levels of nestlings in these populations.<ref>Morinha, F., Ramos, P. S., Gomes, S., Mannan, R. W., Guedes-Pinto, H., & Bastos, E. (2016). ''Microsatellite markers suggest high genetic diversity in an urban population of Cooper's hawks (Accipiter cooperii)''. Journal of genetics, 95(1), 19–24.</ref><ref>Bielefeldt, J., & Rosenfield, R. N. (2000). ''Comment: comparative breeding ecology of Cooper's hawks in urban vs. exurban areas of southeastern Arizona''. Journal of Wildlife Management, 64(2), 599–600.</ref>

===Longevity and parasitism===
Cooper's hawks can be a long-living bird. Some authors credit lifespans of up to 8 years of age in the wild.<ref name= Palmer/><ref>Kennard, J. H. (1975). ''Longevity records of North American birds''. Bird-banding, 55–73.</ref> The oldest recorded bird recorded among migrants that bred in Oregon was 10 years and 5 months old.<ref name= Henny2/> The oldest recorded breeding bird was a 12-year-old female in British Columbia while the oldest recorded wild bird was 20 years, 5 months old, banded in migration.<ref name= Rosenfield8/><ref>Lutmerding, J. A., & Love, A. S. (2016). ''Longevity Records of North American Birds''. Version 2016.1. Laurel, MD: Patuxent Wildlife Research Center. Bird Banding Laboratory.</ref> However, the mean age at death recorded in 136 banded Cooper's hawks was 16.3 months.<ref>Keran, D. (1981). ''The incidence of man-caused and natural mortalities to raptors''. Raptor Research, 15 :108–112.</ref> It was estimated for the species that the mortality rate in the first year of life for these hawk is 71–78% while it about 34–37% in the subsequent years.<ref name= Henny3/> An annual survival rate of 75% was recorded for juvenile males in Tucson while the survival rate for juvenile female here was 64%. The survival rate for Tucson adults was between 69 and 88%.<ref name= Mannan2/><ref name= Recruitment/> 75% was considered the survival rate of wintering Cooper's hawks in Indiana and southern Illinois but mean mortality between adults and juveniles was estimated to possibly average up to 46.4%.<ref name= Roth/><ref name= Roth5>Roth, T. C., Lima, S. L., & Vetter, W. E. (2005). ''Survival and causes of mortality in wintering Sharp-shinned Hawks and Cooper's Hawks''. The Wilson Journal of Ornithology, 117(3), 237–244.</ref> The annual survival rate in Albuquerque was 27–38% for female immatures.<ref name= Matter/> No correlation was found to body size or habitat in female survivorship but those in Wisconsin who changed nest sites annually may have had slightly higher survival rates than those who reused a same nest site.<ref name= Rosenfield4/> The opposite trend was reported for north Florida, wherein females who reused a nest site seemed to have higher survival rates.<ref name= Millsap/> Historic survival rates (1925–1940) as reported were much lower, with extensive persecution causing an annual mortality that was estimated at 44%.<ref name= Palmer/><ref name= Henny3/> Regular natural causes of mortality in Cooper's hawk, mainly of their young, include [[hypothermia]], [[Storm|windstorms]] and [[Snag (ecology)|tree collapses]].<ref name= Palmer/><ref name= Reynolds6/> Clashes between members of the same sex can be lethal, especially those between two males.<ref name= Rosenfield4/><ref name= Millsap/><ref name= Boal4/> Although Cooper's hawks are not known to prey on [[venomous snake]]s, one was found dead from envenomation next to a burrow holding both a [[Agkistrodon contortrix|copperhead]] (''Agkistrodon contortrix'') and an [[eastern diamondback rattlesnake]] (''Crotalus adamanteus'').<ref>Heckel, J. O., Sisson, D. C., & Quist, C. F. (1994). ''Apparent fatal snakebite in three hawks''. Journal of wildlife diseases, 30(4), 616–619.</ref> Hunting accidents can frequently cause injury, especially in the form of potentially hobbling [[bone fracture]]s, or sometimes can kill Cooper's hawks, especially those living in urban areas.<ref name= Dwyer>Dwyer, J. F., Hindmarch, S., & Kratz, G. E. (2018). ''Raptor mortality in urban landscapes''. In ''Urban Raptors'' (pp. 199–213). Island Press, Washington, DC.</ref><ref>Bedrosian, B. E., & Pierre, A. M. S. (2007). ''Frequency of injuries in three raptor species wintering in northeastern Arkansas''. The Wilson Journal of Ornithology, 119(2), 296–298.</ref><ref name= French>Roth, A. J., Jones, G. S., & French, T. W. (2002). ''Incidence of naturally-healed fractures in the pectoral bones of North American accipiters''. Journal of Raptor Research, 36(3), 229–230.</ref><ref>Morishita, T. Y., Fullerton, A. T., Lowenstine, L. J., Gardner, I. A., & Brooks, D. L. (1998). ''Morbidity and mortality in free-living raptorial birds of northern California: a retrospective study, 1983–1994''. Journal of Avian Medicine and Surgery, 78–81.</ref> In Indiana and Illinois, mortality from collisions were somewhat more prevalent in Cooper's hawks than in sharp-shinned hawks but instances of predation on immature sharp-shins were three times more prevalent than predations on immature Cooper's.<ref name= Roth5/> Despite the risks of urban living, evidence indicates that urban Cooper's seem to be relatively successful, have moderate to low annual survival and reproduce prolifically.<ref name= Stout3/> Cooper's hawks are known to be vulnerable to [[West Nile virus]] with some regularity but sometimes are able to survive despite the viral antibodies being found.<ref>Anderson, J. F., Andreadis, T. G., Vossbrinck, C. R., Tirrell, S., Wakem, E. M., French, R. A., Garmendia, A.E. & Van Kruiningen, H. J. (1999). ''Isolation of West Nile virus from mosquitoes, crows, and a Cooper's hawk in Connecticut''. Science, 286(5448), 2331–2333.</ref><ref>Stout, W. E., Cassini, A. G., Meece, J. K., Papp, J. M., Rosenfield, R. N., & Reed, K. D. (2005). ''Serologic evidence of West Nile virus infection in three wild raptor populations''. Avian Diseases, 49(3), 371–375.</ref><ref>Wiinschmann, A., Shivers, J., Bender, J., Carroll, L., Fuller, S., Saggese, M., & Redig, P. (2004). ''Pathologic findings in red-tailed hawks (Buteo jamaicensis) and Cooper's hawks (Accipiter cooperii) naturally infected with West Nile virus''. Avian Dis, 48, 570–580.</ref><ref>Hull, J., Ernest, H., Hull, J., Hull, A., Reisen, W., Fang, Y., & Ernest, H. (2006). ''Variation of West Nile virus antibody prevalence in migrating and wintering hawks in central California''. The Condor, 108(2), 435–439.</ref> Some mortality from West Nile has been reported, unsurprisingly.<ref>Foss, L., Padgett, K., Reisen, W. K., Kjemtrup, A., Ogawa, J., & Kramer, V. (2015). ''West nile virus–related trends in avian mortality in California, USA, 2003–12''. Journal of wildlife diseases, 51(3), 576–588.</ref> Fatal infections of the [[Herpes simplex virus|herpes virus]] have been recorded at least twice in Cooper's hawks.<ref>Pinkerton, M. E., Wellehan Jr, J. F., Johnson, A. J., Childress, A. J., Fitzgerald, S. D., & Kinsel, M. J. (2008). ''Columbid herpesvirus-1 in two Cooper's hawks (Accipiter cooperii) with fatal inclusion body disease''. Journal of wildlife diseases, 44(3), 622–628.</ref> Cooper's hawks, along with [[great horned owl]]s, had the greatest [[seroprevalence]] of ''[[Avipoxvirus]]'' among several raptorial birds in Illinois.<ref name= Wrobel>Wrobel, E. R., Wilcoxen, T. E., Nuzzo, J. T., & Seitz, J. (2016). ''Seroprevalence of avian pox and Mycoplasma gallisepticum in raptors in central Illinois''. Journal of Raptor Research, 50(3), 289–294.</ref>

An extremely high amount of ''[[Trichomoniasis]]'' was found in nestlings in southeast Arizona. The bacteria was recorded in 95% of urban Cooper's hawk nestlings (though only 8% of non-urban ones) and caused about 50% of recorded nestling deaths, probably roughly doubling the nestling mortality rate compared to the non-urban areas.<ref name= Mannan/><ref name= Dwyer/><ref>Boal, C. W., Mannan, R. W., & Hudelson, K. S. (1998). ''Trichomoniasis in Cooper's hawks from Arizona''. Journal of Wildlife Diseases, 34(3), 590–593.</ref><ref>Bradley, C. A., Gibbs, S. E., & Altizer, S. (2008). ''Urban land use predicts West Nile virus exposure in songbirds''. Ecological Applications, 18(5), 1083–1092.</ref> Adults are less vulnerable to ''Trichomoniasis'' infections but there was no variability to be found by sex, time of year or by location.<ref>Taylor, M. J., Mannan, R. W., U'Ren, J. M., Garber, N. P., Gallery, R. E., & Arnold, A. E. (2019). ''Age-related variation in the oral microbiome of urban Cooper's hawks (Accipiter cooperii)''. BMC microbiology, 19(1), 47.</ref><ref>Gerhold, R. W., Yabsley, M. J., Smith, A. J., Ostergaard, E., Mannan, W., Cann, J. D., & Fischer, J. R. (2008). ''Molecular characterization of the Trichomonas gallinae morphologic complex in the United States''. Journal of Parasitology, 94(6), 1335–1341.</ref> In Wisconsin and British Columbia only 2.7% of 145 studied nestlings had ''Trichomoniasis''.<ref>Rosenfield, R. N., Bielefeldt, J., Rosenfield, L. J., Taft, S. J., Murphy, R. K., & Stewart, A. C. (2002). ''Prevalence of Trichomonas gallinae in nestling Cooper's Hawks among three North American populations''. The Wilson Bulletin, 145–147.</ref><ref>Rosenfield, R. N., Taft, S. J., Stout, W. E., Driscoll, T. G., Evans, D. L., & Bozek, M. A. (2009). ''Low prevalence of Trichomonas gallinae in urban and migratory Cooper's Hawks in northcentral North America''. The Wilson Journal of Ornithology, 121(3), 641–644.</ref><ref>Murphy, R. K., & Stewart, A. C. (2002). ''Prevalence of Trichomonas gallinae in Nestling Cooper's Hawks among Three North American Populations''. Wilson Bulletin, 114 (1): 145–147.</ref> A high balance of the bacterial disease ''[[Mycoplasma gallisepticum]]'', common to birds who frequent [[bird feeder]]s, was found in Cooper's hawks (transmitted from their prey) studied in Illinois (the highest of any six raptor species studied) however effective antibodies were found and no external infection was noted.<ref name= Wrobel/> A high balance of bacterial flora were found the airways of 10 Cooper's hawks, including many with ''[[Salmonella]]'' (rarely fatal in hawks but can compromise their condition).<ref>Lamberski, N., Hull, A. C., Fish, A. M., Beckmen, K., & Morishita, T. Y. (2003). ''A survey of the choanal and cloacal aerobic bacterial flora in free-living and captive red-tailed hawks (Buteo jamaicensis) and Cooper's hawks (Accipiter cooperii)''. Journal of Avian Medicine and Surgery, 17(3), 131–135.</ref> 91% of 47 tested adults in Wisconsin had ''[[Leucocytozoon|Leucocytozoon toddi]]'' and 62% had ''[[Haemoproteus]]'' but only 12% of 33 nestlings there had parasites.<ref>Taft, S.J., Rosenfield, R.N. & Bielefeldt, J. (1994). ''Avian hematozoa of adult and nestling Cooper's Hawks (Accipiter cooperii) in Wisconsin''. J. Helminth. Soc. Washington 61.</ref><ref>Sehgal, R. N., Hull, A. C., Anderson, N. L., Valkiūnas, G., Markovets, M. J., Kawamura, S., & Tell, L. A. (2006). ''Evidence for cryptic speciation of Leucocytozoon spp.(Haemosporida, Leucocytozoidae) in diurnal raptors''. Journal of Parasitology, 92(2), 375–379.</ref> A similar blood parasite infection rate was found in northern New York (and California) as well. Compared to sharp-shinned hawks, while migrating off [[Lake Ontario]], Cooper's hawks were found to have higher [[white blood cell]] counts ([[heterophile]]s, [[monocyte]]s, and [[eosinophil]]s) that may have made them more vulnerable to blood parasitism.<ref name= Phalen>Phalen, D. N., Taylor, C., Phalen, S. W., & Bennett, G. F. (1995). ''Hemograms and hematozoa of sharp-shinned (Accipiter striatus) and Cooper's hawks (Accipiter cooperii) captured during spring migration in northern New York''. Journal of Wildlife Diseases, 31(2), 216–222.</ref><ref>Valkiūnas, G., Sehgal, R. N., Iezhova, T. A., & Hull, A. C. (2010). ''Identification of Leucocytozoon toddi group (Haemosporida: Leucocytozoidae), with remarks on the species taxonomy of leucocytozoids''. Journal of Parasitology, 96(1), 170–177.</ref> ''[[Haematozoa]]'' infection rates were also higher in adults than they were in nestlings in Arizona.<ref>Boal, C. W., Hudelson, K. S., Mannan, R. W., & Estabrook, T. S. (1998). ''Hematology and hematozoa of adult and nestling Cooper's hawks in Arizona''. Journal of Raptor Research, 32, 281–285.</ref><ref>Boughton, D. C., Boughton, R. B., & Volk, J. (1938). ''Avian hosts of the genus Isospora (Coccidiida)''.</ref> Blood parasites were recorded to be higher for later migrating Cooper's hawks in northern New York but were, on the contrary, higher in earlier migrating hawks in [[Marin County, California]].<ref name= Phalen/><ref>Ishak, H. D., Loiseau, C., Hull, A. C., & Sehgal, R. N. (2010). ''Prevalence of blood parasites in migrating and wintering California hawks''. Journal of Raptor Research, 44(3), 215–223.</ref> Even rare parasites such as ''[[Sarcocystis]]'' may be found in wild Cooper's hawks, being apparently more prevalent in juvenile hawks and slightly more often afflicting females rather than males.<ref>Lindsay, D. S., Verma, S. K., Scott, D., Dubey, J. P., & von Dohlen, A. R. (2017). ''Isolation, molecular characterization, and in vitro schizogonic development of Sarcocystis sp. ex Accipiter cooperii from a naturally infected Cooper's hawk (Accipiter cooperii)''. Parasitology international, 66(2), 106–111.</ref><ref>von Dohlen, A. R., Scott, D., Dubey, J. P., & Lindsay, D. S. (2019). ''Prevalence of Sarcocysts in the Muscles of Raptors from a Rehabilitation Center in North Carolina''. Journal of Parasitology, 105(1), 11–16.</ref> [[Parasitic worm|Helminths]] were quite diverse in Cooper's hawks from Florida.<ref>Foster, G. W., & Forrester, D. J. (1995). ''Parasitic helminths of six species of hawks and falcons in Florida''. Journal of Raptor Research, 29, 117–122.</ref> In Minnesota and Wisconsin, several helminths were recorded and there was one instance of a tissue reaction from ''[[Diplotriaenidae|Serratospiculum]]'' as well as a case was reported of related ''[[Diplotriaenidae|Serratospiculoides]]'' in an injured Cooper's hawk in [[Yellowstone National Park]].<ref>Sterner, M. C., & Espinosa, R. H. (1988). ''Serratospiculoides amaculata in a Cooper's hawk (Accipiter cooperii)''. Journal of Wildlife Diseases, 24(2), 378–379.</ref><ref>Taft, S. J., Suchow, K., & Van Horn, M. (1993). ''Helminths from some Minnesota and Wisconsin raptors''. Journal of the Helminthological Society of Washington, 60(2), 260–263.</ref>

==Status and conservation==
===Historic status===
[[File:Accipiter cooperii Quebec.jpg|upright|thumb|Immature Cooper's hawk in winter]]
Cooper's hawks have had an erratic status throughout the 20th into the 21st centuries.<ref name=BOW/> Historic data shows a threefold increase, roughly, around 1920.<ref name= Bent/> However, mortality rates shot up soon after as some authors consider the annual rate of mortality due largely to legalized direct persecution ([[poison]]ing, "pole trapping" and, especially, [[Hunting|shooting]]) between 1925 and 1957 could range up to 60.5–77.6% in the most severe years.<ref name= Palmer/><ref name= Henny3/> The amount of hawks shot down within different populations was estimated at 12 to 40%.<ref name= Henny2/><ref name= Henny3/> Migration counts during the 1930s showed a strong downward trend, and an even worse decline for Cooper's hawk was observed during the late 1950s.<ref>Spofford, W. R. (1969). ''Hawk Mountain counts as population indices in northeastern America''. In ''Peregrine Falcon Populations: Their Biology and Decline'' (J. J. Hickey, Editor). University of Wisconsin Press, Madison, WI, USA. pp. 232–332.</ref><ref>Nagy, A. C. (1977). ''Population trend indices based on 40 years of autumn counts at Hawk Mountain Sanctuary in northeastern Pennsylvania''. In ''Proceedings of the World Conference on Birds of Prey'' (R. D. Chancellor, Editor), Vienna, Austria. International Council Bird Preservation, Hampshire, United Kingdom. pp. 243–253.</ref><ref>Bednarz, J. C., D. Klem Jr., L. J. Goodrich, and S. E. Senner (1990). ''Migration counts of raptors at Hawk Mountain, Pennsylvania, as indicators of population trends, 1934–1986''. Auk 107:96–109</ref> Most Cooper's hawks reacted to heavy persecution by behaving with more shyness and elusiveness.<ref name=BOW/> Much of the human animosity towards Cooper's hawks was due to their hunting of [[Galliformes|gamebirds]] such as [[New World quail|quail]] which human hunters themselves coveted. Furthermore, even ornithological writings from these times reveal a strong [[bias]] against the hawks for their hunting of admired small birds.<ref name= Palmer/><ref name= Bent/><ref>Edminster, F. C. (1939). ''The effect of predator control on ruffed grouse populations in New York''. The Journal of Wildlife Management, 3(4), 345–352.</ref> However, several studies have determined that Cooper's hawk predation is not detrimental to healthy gamebird population, and that most of the blame must fall directly on overexploitation and habitat destruction of humans themselves, with a more recently quantified causal of [[Global warming|changing climate]] further exacerbating the gamebirds' declines.<ref>Brennan, L. A. (1991). ''How can we reverse the northern bobwhite population decline?'' Wildlife Society Bulletin (1973–2006), 19(4), 544–555.</ref><ref>Moss, R., Storch, I., & Müller, M. (2010). ''Trends in grouse research''. Wildlife Biology, 16(1), 1–11.</ref><ref>Williams, C. K., Ives, A. R., Applegate, R. D., & Ripa, J. (2004). ''The collapse of cycles in the dynamics of North American grouse populations''. Ecology Letters, 7(12), 1135–1142.</ref> Human hunting of Cooper's hawk declined when governmental protection of the species was instituted in the late 1960s (nearly two decades after some less controversial birds of prey species were protected in America).<ref name= Palmer/><ref name= Henny3/>

However, instead of the expected gradual recovery, in the 1960s to 1970s, the breeding success rate dropped, in almost certain correlation with man's use of chemical [[biocide]]s, mostly [[DDT]]. Raptorial birds which predominantly prey on either birds or fish were severely affected by the DDT biocide. The concentrations of [[organochlorine]]s like DDT were high in all American ''Accipiter'' and ''Astur'' species, averaging at intermediate levels in Cooper's (0.11&nbsp;mg/kg) but could include the highest known in the group at up to 1.5&nbsp;mg/kg.<ref>Elliott, J. E., & Martin, P. A. (1994). ''Chlorinated hydrocarbons and shell thinning in eggs of (Accipiter) hawks in Ontario, 1986–1989''. Environmental Pollution, 86(2), 189–200.</ref> A considerable average reduction in eggshell thickness was measured to average at around 7%.<ref name= Anderson>Anderson, D. W. & Hickey, J.J. (1972). ''Eggshell changes in certain North American birds''. Proc XVth Int Orn Congr, 514–540.</ref> A particularly severe reduction in eggshell thickness was recorded in New York state, at an average of 19.02%.<ref>Lincer, J. L., & Clark, R. J. (1978). ''Organochlorine residues in raptor eggs in the Cayuga Lake Basin, New York''. New York Fish and Game Journal (USA).</ref><ref>Pattee, O. H., Fuller, M. R., & Kaiser, T. E. (1985). ''Environmental contaminants in eastern Cooper's hawk eggs''. The Journal of wildlife management, 49(4), 1040–1044.</ref> The survival of the species, especially in the eastern part of the continent, was seriously questioned in the 1960s and 1970s.<ref name= Ferguson-Lees/><ref name= Snyder2/> Fewer dramatic ebbs were detected during the height of DDT use in the western part of North America overall, perhaps because of less overall reliance on bird prey.<ref name= Snyder4/><ref>Jones, S. (1979). ''The accipiters-Goshawk, Cooper's Hawk, Sharp-shinned Hawk''. U.S. Bureau of Land Management.</ref><ref>Fuller, M. R. & Mosher, J. A. (1981). ''Methods of detecting and counting raptors: A review''. In ''Estimating Numbers of Terrestrial Birds'' (C. J. Ralph and J. M. Scott, Editors). Studies in Avian Biology 6. pp. 235–246.</ref> Nonetheless, 11 of 16 eggs in Arizona and New Mexico broke due to this cause.<ref name= Snyder4>Snyder, N. F., Snyder, H. A., Lincer, J. L., & Reynolds, R. T. (1973). ''Organochlorines, heavy metals, and the biology of North American accipiters''. BioScience, 23(5), 300–305.</ref> Subsequent to the prohibition of DDT use in North America, the population increased exponentially in the 1980s and 1990s and ultimately was thought to stabilize.<ref name= Ferguson-Lees/><ref name= Stout3/> Data from [[Hawk Mountain Sanctuary]] shows that Cooper's hawk has recovered from DDT more gradually than the sharp-shinned hawk here.<ref>Bolgiano, N. C. (1997). ''Pennsylvania CBC counts of Sharp-shinned and Cooper's Hawks''. Pennsylvania Birds, 610.</ref>

===Current status===
In the 1990s, it was estimated that Cooper's hawks may number "well into six figures" due to their regular distribution over 8 million square kilometers.<ref name= Ferguson-Lees/> Today, Cooper's hawk is thought to number around 800,000 in the United States and Canada.<ref name= Rosenberg>Rosenberg, K. V., Kennedy, J. A., Dettmers, R., Ford, R. P., Reynolds, D., Alexander, J. D., Beardmore, C. J., Blancher, P. J., Butcher, G. S., Camfield, A. F., Couturier, A., Demarest, D. W., Easton, W. E., Giomoco, J. J., Keller, R. H., Mini, A. E., Panjabi, A. O., Pashley, D. N., Rich, T. D., Ruth, J. M., Stabins, H., Stanton, J. & Wills T. (2016). ''Partners in flight landbird conservation plan: 2016 revision for Canada and continental United States''. Partners in Flight Science Committee, 35.</ref> These estimates were gained cross-referencing the number of hectares per active nest, which was in the range of {{convert|101|to|2326|ha|acre|abbr=on}} in the western states and {{convert|272|to|5000|ha|acre|abbr=on}} in the Midwestern and eastern states, as well as data from [[Christmas Bird Count]]s and migration counts.<ref name=BOW/><ref name= Rosenberg/> Evidence from long-time migration counts at [[Bake Oven Knob]] show slight peaks at intervals of 3 to 4 years, however no dramatic declines have been detected since the 1980s.<ref name=BOW/><ref>Heintzelman, D. S. (1986). ''The migrations of hawks''. Indiana University Press.</ref> Following their historic decline, [[Breeding Bird Survey]]s have tracked strong increases of the breeding population (upward trends from 1.2% in California to 4.4% in Pennsylvania) in six states, with a 2.2% increase overall, and similar trends in multiple other states. In many states (Arizona, California, Florida, Missouri, New Mexico and North Dakota) the numbers are probably similar or greater to those prior to 1945.<ref name= Sauer/><ref name= Mannan/><ref name= Recruitment/><ref>Murphy, R. K. (1993). ''History, nesting biology, and predation ecology of raptors in the Missouri Coteau of northwestern North Dakota''. PhD dissertation, Montana State University, Bozeman, MT, USA.</ref><ref>McCabe, J. D., Yin, H., Cruz, J., Radeloff, V., Pidgeon, A., Bonter, D. N., & Zuckerberg, B. (2018). ''Prey abundance and urbanization influence the establishment of avian predators in a metropolitan landscape''. Proceedings of the Royal Society B, 285(1890), 20182120.</ref> It is thought that the population of Cooper's hawks in Wisconsin is nearly saturated relative to the landmass of the state, after a rough 25-fold increase since the late 1970s.<ref name= Bozek/><ref name= Stout3/> Based largely on data from well-known populations such as Tucson and Milwaukee, some authors opine that Cooper's hawk may be the most common raptor in American urban areas today, although surely other common raptorial birds such as red-tailed hawks, American kestrels and [[turkey vulture]]s (''Cathartes aura'') may easily rival them in this regard.<ref name=BOW/><ref name= Sauer/><ref name= Sutton/><ref name= Rosenfield8/><ref name= Stout3/>

===Potential threats===
Shooting is now a generally insignificant cause of mortality though is still sometimes reported.<ref name=BOW/><ref name=Hoffman2/><ref name=Status/><ref>Evans, D. L. (1982). ''Status reports on twelve raptors''. U.S. Fish and Wildlife Service Special Scientific Report no. 238, Washington, DC, USA.</ref> Despite the declining effect of pesticides on Cooper's hawk's overall population, lingering harmful effect from [[dieldrin]] has been indicated in some hawks in British Columbia and recently some hawks have been killed by the pesticide [[warfarin]].<ref name= Brogan>Brogan, J. M., Green, D. J., Maisonneuve, F., & Elliott, J. E. (2017). ''An assessment of exposure and effects of persistent organic pollutants in an urban Cooper's hawk (Accipiter cooperii) population''. Ecotoxicology, 26(1), 32–45.</ref><ref>Deem, S. L., Terrell, S. P., & Forrester, D. J. (1998). ''A retrospective study of morbidity and mortality of raptors in Florida: 1988–1994''. Journal of Zoo and Wildlife Medicine, 160–164.</ref> [[Bioaccumulation]] of [[pollutant]]s may still have considerable effect on this species.<ref name= Fremlin/> Declines due to pollutants are seemingly occurring for Cooper's hawks living in [[Vancouver]].<ref name= Brogan/> Recent cases of [[cyanide]] poisoning of Cooper's hawks have been reported.<ref>Franson, J. C. (2017). ''Cyanide poisoning of a Cooper's hawk (Accipiter cooperii)''. Journal of Veterinary Diagnostic Investigation, 29(2), 258–260.</ref> [[Lead poisoning]] can sometimes threaten Cooper's hawks, through lead bullets left in dead or injured game.<ref>McBride, T. J., Smith, J. P., Gross, H. P., & Hooper, M. J. (2004). ''Blood-lead and ALAD activity levels of Cooper's Hawks (Accipiter cooperii) migrating through the southern Rocky Mountains''. Journal of Raptor Research, 38, 118–124.</ref>

[[File:Cooper S Hawk In Hdr (109143361).jpeg|thumb|right|A high risk of wire collision is present for Cooper's hawks dwelling in urban vicinities.]]
Most urban-related mortality for Cooper's hawks is likely to be collisions with manmade objects. These are mostly wire strikes (with or without resulting [[electrocution]]), [[automobile collision]]s and window strikes or with other parts of manmade structure while distractingly hunting.<ref name= Dwyer/><ref name= French/> 70.8% of diagnosed mortality for Cooper's hawks of yearling age or older in Tucson was from such collisions.<ref name= Mannan/> In less developed regions, such as much of Montana, the rate of wire collisions and electrocutions was considerably lower for Cooper's hawks than for various other birds of prey who are either larger-bodied and/or use less forested areas.<ref>O'Neil, T. A. (1988). ''An analysis of bird electrocutions in Montana''. Journal of Raptor Research, 22(1), 27–28.</ref><ref>Harness, R. (1996). ''Raptor Electrocutions on Electric Utility Distribution Overhead Structures''. In ''Proceedings of Rural Electric Power Conference'' (p. B4). IEEE.</ref> Other studies support that the number of fatal window and wire collisions of urban-living Cooper's hawks is "excessively high".<ref>Hager, S. B. (2009). ''Human-related threats to urban raptors''. Journal of Raptor Research, 43(3), 210–226.</ref> Cooper's hawks found in the vicinity of airports are at risk of [[bird strike]] with aircraft, therefore 185 Cooper's were [[Species translocation|translocated]] away from these areas (the 5th most frequently translocated raptor species).<ref>Schafer, L. M., & Washburn, B. E. (2016). ''Managing raptor-aircraft collisions on a grand scale: summary of a Wildlife Services raptor relocation program''. In Proceedings of the Vertebrate Pest Conference (Vol. 27, No. 27).</ref> A similar translocation effort away from the [[Los Angeles basin]] around the [[Los Angeles International Airport]] translocated 349 Cooper's hawks (about a fifth of all translocated raptors), apparently successfully.<ref>Biteman, D. S., Collins, D. T., & Washburn, B. E. (2018). ''Sunshine, Beaches, and Birds: Managing Raptor-Aircraft Collisions at Airports in Southern California''. In ''Proceedings of the Vertebrate Pest Conference'' (Vol. 28, No. 28).</ref> Cooper's hawks are sometimes displaced by the placement of [[wind farm]]s, with studies indicating that Cooper's need about seven years to locally recover from such displacement.<ref>Dohm, R., Jennelle, C. S., Garvin, J. C., & Drake, D. (2019). ''A long‐term assessment of raptor displacement at a wind farm''. Frontiers in Ecology and the Environment, 17(8), 433–438.</ref> [[Synurbization]] has been detected in Cooper's hawks as, despite the dangers of various kinds of collisions, it has been found that in favorable urban areas, hawks of the species can seem to breed more closer to one another, gather more food and produce more young on average than those outside such areas.<ref name= Estes/><ref name= Rosenfield8/><ref>Ditchkoff, S. S., Saalfeld, S. T., & Gibson, C. J. (2006). ''Animal behavior in urban ecosystems: modifications due to human-induced stress''. Urban ecosystems, 9(1), 5–12.</ref><ref>Neese, M. R., Seitz, J., Nuzzo, J., & Horn, D. J. (2008). ''Population trends of raptors admitted to the Illinois Raptor Center, 1995–2005''. Transactions of the Illinois State Academy of Science, 101(3–4), 217–224.</ref> Even New York City has seen (if erratically present) since the late 1990s, a return of nesting Cooper's hawks.<ref>DeCandido, R., & Allen, D. (2005). ''First nesting of Cooper's hawks (Accipiter cooperii) in New York City since 1955''. Journal of Raptor Research, 39, 109.</ref>

[[File:Accipiter cooperii Bonaparte.jpg|thumb|left|A Cooper's hawk of the ample [[Tucson]] population.]]
Logging may decrease some populations but the overall effect it has on Cooper's hawks is generally considered unknown.<ref name=BOW/><ref name= Reynolds/><ref name= Rosenfield10/> As with all ''Astur'' and ''Accipiter'' species, Cooper's hawks can presumably only withstand a certain level of [[habitat loss|loss of habitat]] before an area becomes essentially unlivable.<ref name= Ferguson-Lees/> Studies in Arizona determined that heavily grazed agricultural areas were favored over lightly grazed ones due to greater prey concentrations in the latter habitats.<ref name= Millsap2/> On the contrary, in the early 1990s (while the species was generally recovering), the species was considered to be "state-endangered" in New Jersey, with ongoing harmful effects found for poorly regulated (or entirely unregulated) logging and land development within {{convert|40|to|120|m|ft|abbr=on}} of active nests.<ref name= Speiser>Bosakowski, T., Speiser, R., Smith, D. G., & Niles, L. J. (1993). ''Loss of Cooper's Hawk Nesting Habitat to Suburban Development: Inadequate Protection for a State-Endangered Species''. Journal of Raptor Research, 27(1), 26–30.</ref> In the [[Black Hills]], harvesting of [[Pinus ponderosa|ponderosa pines]] appears to be causing Cooper's, sharp-shins and goshawks to vacate large parts of the forest.<ref>Dykstra, B. L. (1996). ''Effects of harvesting ponderosa pine on birds in the Black Hills of South Dakota and Wyoming''.</ref> It has been recommended that a buffer zone of at least {{convert|200|to|240|m|ft|abbr=on}}, with a median estimated space needed of about {{convert|525|m|ft|abbr=on}}, should be free from human disturbance or development to retain the protected nests of Cooper's hawks.<ref name= James/><ref name= Speiser/><ref>Richardson, C. T., & Miller, C. K. (1997). ''Recommendations for protecting raptors from human disturbance: a review''. Wildlife Society Bulletin (1973–2006), 25(3), 634–638.</ref> Studies in New Mexico showed that these hawks are reliant on the conservation of riparian woodlands in much of the southern part of the state.<ref>Smith, E. L., Hoffman, S. W., Stahlecker, D. W., & Duncan R. B. (1996). ''Results of a raptor survey in southwestern New Mexico''. J. Raptor Res, 30(4), 183–188.</ref> Despite the large, productive and genetically diverse population of Cooper's hawks in Tucson, several authors have hypothesized, controversially, that the city is an [[ecological trap]], due to the unsustainably high turnover for nestlings via ''[[Trichomoniasis]]''-related mortality and for adults via frequent lethal collisions.<ref name= Mannan/><ref name= Boal3/><ref>Ames, J., Feiler, A., Mendoza, G., Rumpf, A., & Wirkus, S. (2011). ''Determination of Tucson, Arizona as an Ecological Trap for Cooper's Hawks (Accipiter cooperii)''.</ref>

Quite few Cooper's hawks have ever been gathered for use in [[falconry]]. This hawk is fairly unpopular in falconry practices due to its high-strung personality and is additionally considered in such captive conditions as given towards "tyrannical", "hysterical" and "demanding" behaviors, even compared to its similarly disposed larger cousin, the [[American goshawk]], which is fairly popular in falconry.<ref>Peyton, R. B., Vorro, J., Grise, L., Tobin, R., & Eberhardt, R. (1995). ''A profile of falconers in the United States: Falconry practices, attitudes and conservation behaviors''. In ''North American Wildlife and Natural Resources Conference'' (USA).</ref><ref>Bodio, S. (1984). ''A Rage for Falcons''. Nick Lyons Books, New York, NY, USA.</ref><ref>McElroy, H. (1977). ''Desert hawking II''. Privately published, Yuma, AZ, USA.</ref><ref>McLeran, V. (2000). ''The Cooper's Hawk: a cross timbers chronical''. XLibris, Philadelphia, PA, USA.</ref>

===Threat to conservation dependent species===
Generally, Cooper's hawks hunt the locally common birds that are available and probably control some birds (such as the more numerous icterids and corvids) that may without the influence of natural predation risk overpopulation and potential harm to ecosystems.<ref name= Palmer/><ref name= Rosenfield8/><ref>McAtee, W. L. (1935). ''Food habits of common hawks'' (No. 370). US Department of Agriculture.</ref> However, as an opportunistic natural predator of almost any North American bird smaller than itself, Cooper's hawk may inadvertently deplete populations of rarer, conservation-dependent species. The [[American kestrel]], whose populations have experienced considerable decrease, may be one species which has suffered from the extensive predation of the recovered Cooper's hawk population.<ref>{{cite web| url= http://www.hawkmountain.org/raptorpedia/hawks-at-hawk-mountain/hawk-species-at-hawk-mountain/american-kestrel/page.aspx?id=498 |title= ''What is an American kestrel?''| website= hawkmountain.org | publisher= Hawk Mountain Sanctuary| access-date= January 28, 2017}}</ref> However, there is no evidence that Cooper's hawk predation is one of the leading causes of kestrel declines and data seems to indicate it is, at most, a localized threat.<ref name= McClure/><ref name= Lesko/><ref>Smallwood, J. A., Causey, M. F., Mossop, D. H., Klucsarits, J. R., Robertson, B., Robertson, S., Mason, J., Maurer, M. J., Melvin, R. J., Dwason, R.D., Bortolotti, G. R., Parrish, J.W., Breen, T. F. & Bond, K. (2009). ''Why are American Kestrel (Falco sparverius) populations declining in North America? Evidence from nest-box programs''. Journal of Raptor Research, 43(4), 274–282.</ref><ref>Sullivan, B. L., & Wood, C. L. (2005). ''The changing seasons – a plea for the common birds''. North American Birds, 59:20–30.</ref> Similarly, Cooper's hawks occasionally prey upon other threatened bird species, and, although said predation is not a primary cause of concern, may exacerbate the already worrying condition of many declining North American birds. Some threatened species known to be thusly hunted by these hawks are [[greater prairie-chicken]]s (''Tympanuchus cupido''),<ref>Bergan, J., Morrow, M. & Rossignol, T. (1993). ''Attwater's Prairie-Chicken Recovery Plan (Tympanuchus cupido attwateri)''. U. S. Fish and Wildlife Service, Southwest Region.</ref> [[lesser prairie-chicken]]s (''Tympanuchus pallidicinctus''),<ref>Behney, A. C., Boal, C. W., Whitlaw, H. A., & Lucia, D. R. (2012). ''Raptor community composition in the Texas Southern High Plains lesser prairie‐chicken range''. Wildlife Society Bulletin, 36(2), 291–296.</ref> [[red-headed woodpecker]]s,<ref>Kilgo, J. C. & Vukovich, M. (2011). F''actors affecting breeding season survival of red-headed woodpeckers in South Carolina''. The Journal of Wildlife Management, 76:328–335.</ref> [[Bell's vireo]] (''Vireo bellii''),<ref>Howell, C. A., & Dettling, M. D. (2009). ''Least Bell's Vireo monitoring, nest predation threat assessment, and cowbird parasitism threat assessment at the San Joaquin River National Wildlife Refuge''. Report to US Fish & Wildlife Service and US Bur. of Reclamation.</ref> [[Florida scrub jay]] (''Aphelocoma coerulescens''),<ref>Woolfenden, G. E. and J. W. Fitzpatrick (1996). ''Florida Scrub-Jay (Aphelocoma coerulescens)'', version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> [[wood thrush]] (''Hylocichla mustelina'') (Cooper's being identified as one three major nest predators along with blue jays and raccoons),<ref>Friesen, L. E., Casbourn, G., Martin, V., & Mackay, R. J. (2013). ''Nest predation in an anthropogenic landscape''. The Wilson Journal of Ornithology, 125(3), 562–569.</ref> [[golden-winged warbler]] (''Vermivora chrysoptera''),<ref>Aldinger, K. R., Bakermans, M. H., Larkin, J. L., Lehman, J., McNeil, D. J., Tisdale, A., & Fearer, T. (2015). ''Monitoring and evaluating Golden-winged Warbler use of breeding habitat created by Natural Resources Conservation Service practices''. Conservation Effects Assessment Program Final Report, USDA Natural Resources Conservation Service.</ref> [[cerulean warbler]] (''Setophaga cerulea'')<ref>Buehler, D. A., P. B. Hamel, and T. Boves (2013). ''Cerulean Warbler (Setophaga cerulea)'', version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.</ref> and [[golden-cheeked warbler]] (''Setophaga chrysoparia'').<ref name= Stake/>

==Images==
<gallery>
File:Cooper's hawk immature.jpg|Cooper's hawk immature
File:Cooper's Hawk in California.jpg|Adult Cooper's hawk
File:Cooper's hawk feeding.jpg|Cooper's hawk feeding on a small bird
</gallery>

==References==
{{Reflist|2}}

==Further reading==
* {{cite book | author=Sibley, David | title=The Sibley Guide to Birds | title-link=The Sibley Guide to Birds | publisher=Knopf | year=2000 | pages=[https://archive.org/details/sibleyguidetobir00sibl_0/page/112 112–113] | isbn=0-679-45122-6 | author-link=David Allen Sibley }}
* {{ITIS | id=175309 | taxon=''Accipiter cooperii'' | access-date=February 22, 2009 }}
*Schmitt, N. John., Clark, William S.., Kiff, Lloyd. Raptors of Mexico and Central America. United States: Princeton University Press, 2017. ISBN 9781400885077
*Wheeler, Brian K.., Clark, William S.. A Field Guide to Hawks of North America. United Kingdom: Houghton Mifflin, 2001. ISBN 9780395670675
*Threatened and Endangered Plants and Animals in New Hampshire's Forested Habitats: A Guide for Foresters and Other Land Managers. United States: University of New Hampshire Cooperative Extension, 2005.
*Edwards, Ernest Preston., Butler, Edward Murrell. A Field Guide to the Birds of Mexico and Adjacent Areas: Belize, Guatemala, and El Salvador, Third Edition. United States: University of Texas Press, 1998. ISBN 9780292720916

==External links==
*[https://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Coopers_Hawk.html Cooper's hawk Species Account] – Cornell Lab of Ornithology
*[https://www.mbr-pwrc.usgs.gov/id/framlst/i3330id.html Cooper's hawk – ''Accipiter cooperii''] – USGS Patuxent Bird Identification InfoCenter
* {{InternetBirdCollection|coopers-hawk-accipiter-cooperii|Cooper's hawk}}
* {{VIREO|Cooper's+Hawk|Cooper's hawk}}
* {{IUCN_Map|22695656/264598871|Accipiter cooperii}}

{{Taxonbar|from=Q862896}}
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[[Category:Astur (bird)]]
[[Category:Birds of prey of North America]]
[[Category:Birds of the United States]]
[[Category:Birds described in 1828]]
[[Category:Taxa named by Charles Lucien Bonaparte]]
[[Category:Articles containing video clips]]
[[Category:Fauna of California]]
[[Category:Least concern biota of the United States]]