View source for Killdeer

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{{featured article}}
{{short description|Shorebird found in the Americas}}
{{Speciesbox
 | status = NT
 | status_system = IUCN3.1
 | status_ref = <ref name="iucn">{{cite iucn |author=BirdLife International |date=2024 |title=''Charadrius vociferus'' |volume=2024 |article-number=e.T22693777A256247816 |doi=10.2305/IUCN.UK.2024-2.RLTS.T22693777A256247816.en |access-date=11 November 2021}}</ref>
 | image = Killdeer Heislerville.png
 | image_caption = Killdeer in breeding plumage.
 | image2 = Charadrius vociferus.ogg
 | genus = Charadrius
 | species = vociferus
 | authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
 | range_map = Charadrius vociferus map.svg
 | range_map_caption = <big>{{leftlegend|#FF7F2A|Breeding range|outline=gray}}{{leftlegend|#7137C8|Resident range|outline=gray}}{{leftlegend|#5F8DD3|Non-breeding range|outline=gray}}</big>
}}

The '''killdeer''' ('''''Charadrius vociferus''''') is a large [[plover]] found in the [[Americas]]. Its shrill, two-syllable call is often heard, sounding like "kill [[deer]]". It was described and given its current scientific name in 1758 by [[Carl Linnaeus]] in the [[10th edition of Systema Naturae|10th edition]] of his ''[[Systema Naturae]]''. Three subspecies are described. Its {{birdgloss|upperparts}} are mostly brown with [[rufous]] fringes, the head has patches of white and black, and two black bands cross the breast. The belly and the rest of the breast are white. The [[nominate subspecies|nominate]] (or originally described) subspecies breeds from southeastern Alaska and southern Canada to Mexico. It is seen year-round in the southern half of its breeding range; the subspecies ''C. v. ternominatus'' is resident in the [[West Indies]], and ''C. v. peruvianus'' inhabits Peru and surrounding South American countries throughout the year. North American breeders winter from their resident range south to Central America, the West Indies, and the northernmost portions of South America.

The nonbreeding habitat of the killdeer includes coastal wetlands, beach habitats, and coastal fields. Its breeding grounds are generally open fields with short vegetation (but locations such as rooftops are sometimes used); although it is a shorebird, it does not necessarily nest close to water. The nest itself is a [[Bird nest#Scrape|scrape]] lined with vegetation and white material, such as pebbles or [[seashell]] fragments. This bird lays a [[clutch (eggs)|clutch]] of four to six buff to beige eggs with dark markings. The breeding season (starting with egg-laying) occurs from mid-March to August, with later timing of egg-laying in the northern portion of the range. Both parents incubate the eggs for 22 to 28 days typically. The young stay in the nest until the day after being hatched, when they are led by their parents to a feeding territory (generally with dense vegetation where hiding spots are abundant), where the chicks feed themselves. The young then [[fledge]] about 31 days after hatching, and breeding first occurs after one year of age.

The killdeer primarily feeds on insects, although other invertebrates and seeds are eaten. It [[foraging|forages]] almost exclusively in fields, especially those with short vegetation and with cattle and standing water. It primarily forages during the day, but in the nonbreeding season, when the moon is full or close to full, it forages at night, likely because of increased insect abundance and reduced predation during the night. [[Predator]]s of the killdeer include various birds and mammals. Its multiple [[responses to predation]] range from the "broken-wing display" (feigning injury to lure a predator away from the nest) to the "[[ungulate]] display" (charging the animal, named for its use against grazing ungulates rather than predators).<ref>{{cite web |author=<!-- not stated -->|title= Killdeers And The Broken Wing Act|work= Bird Spot|url=https://www.birdspot.co.uk/bird-behaviour/killdeers-and-the-broken-wing-act|year=2025|access-date=2025-11-12}}</ref> 

The killdeer was formerly considered a [[least-concern species]] by the IUCN due to its large range and population,<ref name="iucn" /> but is now considered a [[near-threatened species]] due to its population decline,<ref name=iucn/> though the decline is not rapid enough to warrant uplisting the killdeer to a [[vulnerable species]].<ref name="iucn" /> It is protected by the American [[Migratory Bird Treaty Act of 1918]] and the Canadian [[Migratory Birds Convention Act]].

==Etymology and taxonomy==
The killdeer was described in 1758 by Swedish [[naturalist]] [[Carl Linnaeus]] in the [[10th edition of Systema Naturae|10th edition]] of his ''[[Systema Naturae]]'' as ''Charadrius vociferus'',<ref name="Linnaeus"/> its current [[scientific name]].<ref name="hbw"/> Linnaeus' description was based on a 1731 account of it by English naturalist [[Mark Catesby]] in his ''The Natural History of Carolina, Florida and the Bahama Islands'',<ref name="Linnaeus">{{cite book |last= Linnaeus |first=Carl |author-link=Carl Linnaeus |title= Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis |publisher= (Laurentii Salvii) |location=Stockholm, Sweden |volume= 1 |edition= 10th |language= la |year= 1758 |page= 150 |url=https://archive.org/stream/carolilinnaeisy00gesegoog#page/n159/mode/1up |via= The [[Internet Archive]]}}</ref> where he called it the "chattering plover".<ref>{{cite book|url=https://www.biodiversitylibrary.org/item/126524#page/282/mode/1up|title=The Natural History of Carolina, Florida and the Bahama Islands|last=Catesby|first=Mark|year=1731|page=71|location=London|volume=1|publisher=Printed at the expence of the author, and sold by W. Innys and R. Manby, at the West End of St. Paul's, by Mr. Hauksbee, at the Royal Society House, and by the author, at Mr. Bacon's in Hoxton}}</ref> The genus name ''Charadrius'' is [[Late Latin]] for a yellowish bird mentioned in the fourth-century [[Vulgate]] [[Bible]]. This word derives from the [[Ancient Greek]] ''kharadrios'', a bird found in ravines and river valleys (''kharadra'', "ravine"). The specific name '' vociferus '' is  [[Latin]], coming from  ''vox'', "cry", and '' ferre'', "to bear".<ref name=job>{{cite book | last= Jobling | first= James A. | year= 2010| title= The Helm Dictionary of Scientific Bird Names | url= https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling | publisher=Christopher Helm | location = London | isbn = 978-1-4081-2501-4 | pages=[https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling/page/n99 99], 404}}</ref>

Three subspecies are described:
* ''C. v. vociferus'' <small>Linnaeus, 1758</small> – The [[nominate subspecies]] (originally described subspecies), it is found in the US (including southeastern Alaska), southern Canada, Mexico, and with some less widespread grounds further south, to Panama. It winters to northwestern South America.<ref name="hbw"/>
* ''C. v. ternominatus'' <small>Bangs & Kennard, 1920</small> – This subspecies is found on the [[Bahama]]s, the [[Greater Antilles]], and [[Virgin Islands]].<ref name="hbw"/>
* ''C. v. peruvianus'' <small>(Chapman, 1920)</small>{{NoteTag|Originally described as ''Oxyechus vociferus peruvianus''.<ref name="Chapman1920">{{cite journal |last=Chapman|first=Frank M.|title=Description of a proposed new race of the killdeer from the coast of Peru|journal=The Auk|volume=37|issue=1|year=1920|pages=105–108|issn=0004-8038|doi=10.2307/4072966|jstor=4072966 |url=https://www.biodiversitylibrary.org/part/86351}}</ref>
}}  – This South American subspecies is found in western Ecuador, Peru, and extreme northwest Chile.<ref name="hbw" />

The killdeer's call resembles the phrase "kill deer", for which the species is named.<ref name="Hauber2014"/>

==Description==
The killdeer is a large plover, with adults ranging in length from {{convert|20|to|28|cm|in|abbr=on}}, having a [[wingspan]] between {{convert|59|and|63|cm|in|abbr=on}}, and usually being between {{convert|72|and|121|g|oz|abbr=on}} in weight.<ref name="hbw"/> It has a short, thick, and dark bill, flesh-colored legs, and a red eye ring.<ref name="USGSdesc">{{cite web |url=https://www.mbr-pwrc.usgs.gov/infocenter/i2730id.html |title=Killdeer ''Charadrius vociferus'' |publisher=[[USGS]] |website=[[Patuxent Wildlife Research Center]] |access-date=1 August 2018 |archive-date=3 January 2017 |archive-url=https://web.archive.org/web/20170103073415/https://www.mbr-pwrc.usgs.gov/Infocenter/i2730id.html }}</ref>

[[File:Kildeer (6316766771).jpg|thumb|left|In flight]]
Its upper parts are mostly brown with rufous fringes,<ref name="hbw"/> its cap, back, and wings being the former color. It has a white forehead and a white stripe behind the eye, and its [[Lore (anatomy)|lores]] and the upper borders to the white forehead are black. The killdeer also has a white collar with a black upper border. The rest of the face is brown. The breast and belly are white, except for two black breast bands. It is the only plover in North America with two breast bands. The rump is red, and the tail is mostly brown. The latter also has a black [[wikt:subterminal|subterminal]] band, a white [[wikt:terminal|terminal]] band, and barred white feathers on the outer portion of the tail. A white wing stripe at the base of the [[flight feather]]s is visible in flight.<ref name="USGSdesc"/>

The female's mask and breast bands tend to be browner than those of the male. The adult of the subspecies ''C. v. ternominatus'' is smaller, paler, and greyer than the nominate. The subspecies ''C. v. peruvianus'' is smaller than the nominate and has more extensive rufous feather fringes.<ref name="hbw"/> The juvenile is similar to the adult.<ref name="USGSdesc"/> The upper parts of the chicks are colored dusky and buff. Their underparts, forehead, neck, and chin are white,<ref name="hbw"/> and they have a single band across their breast.<ref name="USGSdesc"/>

The killdeer is a vocal species, calling even at night. Its calls include nasal notes, like "deee", "tyeeee", and "kil-deee" (the basis of its common name). During display flights, it repeats a call of "kil-deer" or "kee-deeyu". When this plover is disturbed, it emits notes in a rapid sequence, such as "kee-di-di-di". Its {{birdgloss|alarm call}} is a long, fast trill.<ref name="hbw"/>

==Habitat and distribution==
[[File:Killdeer (Charadrius vociferus ternominatus).JPG|right|thumb|The subspecies ''C. v. ternominatus'' in [[Cuba]]]]
The nominate subspecies of the killdeer breeds in the US (including southeastern Alaska), southern Canada, and Mexico, with less widespread grounds further south, to Panama. Some northern populations are [[Bird migration|migratory]]. This bird is resident in the southern half of its breeding range,<ref name="AlderferHess2011">{{cite book|author1=Jonathan K. Alderfer|author2=Paul Hess|title=National Geographic Backyard Guide to the Birds of North America|url=https://books.google.com/books?id=oPMDsPn6fjQC|year=2011|publisher=National Geographic|isbn=978-1-4262-0720-4|page=69}}</ref> found throughout the year in most of the [[contiguous United States]].<ref name="SanzenbacherHaig2001">{{cite journal |last1=Sanzenbacher |first1=Peter M. |last2=Haig |first2=Susan M. |title=Killdeer population trends in North America |journal=Journal of Field Ornithology|volume=72|issue=1 |year=2001 |pages=160–169 |doi=10.1648/0273-8570-72.1.160|s2cid=85684751 |issn=1557-9263}}</ref> It also winters south to Central America, the [[West Indies]], Colombia, Ecuador, and islands off Venezuela, leaving its breeding grounds after mid-July,<ref name="hbw"/> with migration peaking from August to September.<ref name="AlderferHess2011"/> Migration to the breeding grounds starts in February<ref name="Nellis2001">{{cite book|last=Nellis|first=David W.|title=Common Coastal Birds of Florida and the Caribbean|url=https://books.google.com/books?id=-REZ4R8wBg4C&pg=PA211|year= 2001|publisher=Pineapple Press Inc|isbn=1-56164-191-X |page=211}}</ref> and ends in mid-May.<ref name="CampbellDawe1997">{{cite book|last1=Campbell|first1=Robert Wayne|last2=Dawe|first2=Neil K.|last3=McTaggart-Cowan|first3=Ian|last4=Cooper|first4=John M.|last5=Kaiser|first5=Gary W.|last6=McNall|first6=Michael C. E.|title=The Birds of British Columbia: Nonpasserines: Diurnal Birds of Prey Through Woodpeckers|url=https://books.google.com/books?id=U1TRsth_9j0C&pg=PA120|year=1997|publisher=UBC Press|isbn=978-0-7748-4435-2|page=120}}</ref>

The subspecies ''C. v. ternominatus'' is thought to be resident in the Bahamas, [[Greater Antilles]], and [[Virgin Islands]]. ''C. v. peruvianus'' is seen year-round in western Ecuador, Peru, and extreme northwestern Chile.<ref name="hbw"/>

The killdeer uses beach habitats, coastal wetlands, and fields during the non-breeding season.<ref name="jg"/> It forages almost exclusively in these fields, especially those with short vegetation and with cattle (which likely shorten the vegetation) and standing water.<ref name="LongRalph2001"/> When breeding, the killdeer has a {{birdgloss|home range}} of about {{convert|6|ha|acre|abbr=on}}, although this is generally larger when nesting more than {{convert|50|m|ft|abbr=on}} away from water.<ref name="PlissnerOring2000">{{cite journal |last1=Plissner |first1=Jonathan H. |last2=Oring |first2=Lewis W. |last3=Haig |first3=Susan M. |title=Space use of killdeer at a Great Basin breeding area |journal=The Journal of Wildlife Management |volume=64 |issue=2 |year=2000 |page=421 |doi=10.2307/3803240 |jstor=3803240 |bibcode=2000JWMan..64..421P }}</ref> Although generally a low-land species,<ref name="hbw"/> it is found up to the snowline in meadows and open lakeshores during its autumn migration.<ref name="CampbellDawe1997"/>

==Behavior==

===Breeding===
[[File:Killdeer (Charadrius vociferus) copulating - edit1.jpg|left|thumb|Copulation]]
The killdeer forms pairs on its breeding grounds right after arriving.<ref name="Lenington1980"/> Both sexes (although the male more often than the female) advertise in flight with loud "killdeer" calls. The male also advertises by calling from a high spot,<ref name="Mundahl1982"/> scraping out a dummy nest,<ref name="Phillips1972">{{cite journal |last1=Phillips |first1=R.E. |title=Sexual and agonistic behaviour in the killdeer (''Charadrius vociferus'')|journal=Animal Behaviour|volume=20|issue=1|year=1972 |pages=1–9 |doi=10.1016/S0003-3472(72)80166-0|issn=0003-3472}}</ref> and with killdeer flights, where it flies with slow wingbeats across its territory. Ground chases occur when a killdeer has been approached multiple times by another killdeer; similarly, flight chases occur when an individual has been approached from the air. Both are forms of territorial defense.<ref name="Mundahl1982">{{Cite journal| volume = 94| issue = 4| pages = 515–530| last = Mundahl| first = John T.| title = Role specialization in the parental and territorial behavior of the killdeer| journal = The Wilson Bulletin| date = 1982|issn=0043-5643}}</ref>

The killdeer nests in open fields or other flat areas with short vegetation (usually below {{convert|1|cm|in|abbr=on}} tall),<ref name="hbw"/> such as agricultural fields and meadows.<ref name = "jg">{{Cite book |last1= Johnsgard |first1= P.A. |author-link=Paul Johnsgard |title= The Plovers, Sandpipers and Snipes of the World |year= 1981 |publisher= University of Nebraska Press |location= Lincoln |isbn= 0-8032-2553-9 |url-access= registration |url= https://archive.org/details/ploverssandpiper0000john }}</ref> Nests are also sometimes located on rooftops.<ref name="hbw"/> This plover frequently breeds close to where it bred the previous year. The male seems to usually renest in the same area regardless of whether or not he retains the same mate. This does not appear to be true of the female, which has been observed to not use the same territory if she does not have the same mate.<ref name="Lenington1975">{{cite journal |last1=Lenington |first1=Sarah |title=Mate fidelity and nesting site tenacity in the killdeer |journal=The Auk |volume=92 |issue=1 |year=1975 |pages=149–151 |doi=10.2307/4084431 |jstor=4084431|issn=1938-4254|doi-access=free }}</ref> The nest itself is merely a shallow depression<ref name="TPWD"/> or scrape<ref name="hbw"/> in the ground, fringed by some stones and blades of grass.<ref name="TPWD">{{cite web |title= Killdeer |last=Hiller |first=Ilo |work= Texas Parks and Wildlife Department|url=http://www.tpwd.state.tx.us/publications/nonpwdpubs/introducing_birds/killdeer/|year=2008 |access-date=2011-03-01}}</ref> It is generally built with white nesting material instead of darker colors; the function of this is suspected to either help keep the nest cool or conceal it.<ref name="KullJr1977">{{Cite journal | volume = 94| issue = 3| pages = 602–604| last=Kull | first=Robert C. Jr. | title = Color selection of nesting material by killdeer| journal = The Auk| date = 1977|issn=1938-4254}}</ref> In a study of [[piping plover]]s, the former function was supported, as nests were {{convert|2|C-change|sp=us}} to {{convert|6|C-change|sp=us}} cooler than the surrounding ground. The latter function also had some support, as the plovers generally chose pebbles closer in color to the eggs; nests that contrasted more with the ground suffered more predation.<ref name="MayerSmith2009">{{cite journal |last1=Mayer |first1=Paul M. |last2=Smith |first2=Levica M.|last3=Ford|first3=Robert G. |last4=Watterson |first4=Dustin C. |last5=McCutchen|first5=Marshall D.|last6=Ryan |first6=Mark R. |title=Nest construction by a ground-nesting bird represents a potential trade-off between egg crypticity and thermoregulation |journal=Oecologia |volume=159 |issue=4|year=2009 |pages=893–901 |doi=10.1007/s00442-008-1266-9|pmid=19145449|bibcode=2009Oecol.159..893M |s2cid=22438709 |issn=1432-1939}}</ref> When nesting on rooftops, the killdeer may choose a flat roof, or build a nest of raised gravel, sometimes lined with white pebbles or pieces of seashells.<ref name="Fisk1978">{{cite journal |last1=Fisk |first1=Erma J. |title=The growing use of roofs by nesting birds |journal=Bird-Banding |volume=49 |issue=2 |year=1978 |pages=134–141 |doi=10.2307/4512343 |jstor=4512343|issn=2327-1280}}</ref>
[[File:Killdeer (Charadrius vociferus) -female on nest.jpg|thumb|A female on a [[bird nest|nest]] in [[Pennsylvania]]]]
The eggs of the killdeer are typically laid from mid-March to early June in the southern portion of the range, and from mid-April to mid-July in the northern part.<ref name="hbw"/> In both cases, the breeding season itself extends to about August.<ref name="Brunton1988a">{{cite journal |last1=Brunton |first1=Dianne H. |author1-link=Dianne Brunton |title=Sexual differences in reproductive effort: time-activity budgets of monogamous killdeer, ''Charadrius vociferus'' |journal=Animal Behaviour|volume=36|issue=3 |year=1988 |pages=705–717 |doi=10.1016/S0003-3472(88)80153-2|s2cid=53171701 |issn=0003-3472}}</ref> In Puerto Rico, and possibly in other Caribbean islands, breeding occurs year-round.<ref name="hbw"/>

The killdeer lays a [[clutch (eggs)|clutch]] of four to six eggs that are buff to beige, with brown markings and black speckles. The eggs are about {{convert|38|by|27|mm|in|abbr=on}} in size,<ref name="Hauber2014"/> and laid at intervals of 24 to 48 hours.<ref name="hbw"/> The energy expenditure of both sexes is at its highest during egg-laying; the female needs to produce eggs, and the male needs to defend his territory.<ref name="Brunton1988b"/> Both of the sexes are closer to the nest site than usual during egg-laying and incubation, although the male is generally closer than the female during all stages of breeding. This latter fact is likely due to the male's increased investment in nest-site defense.<ref name="PlissnerOring2000"/> Up to five replacement clutches can be laid, and occasionally two broods occur.<ref name="hbw"/> Second broods are usually laid in the nesting territory of the first brood.<ref name="Lenington1980"/> The eggs are incubated for 22 to 28 days<ref name="Hauber2014">{{cite book |last=Hauber |first=Mark E. |title=The Book of Eggs: A Life-Size Guide to the Eggs of Six Hundred of the World's Bird Species |url=https://books.google.com/books?id=evQvBAAAQBAJ |year=2014 |publisher=University of Chicago Press |location=Chicago |isbn=978-0-226-05781-1 |page=140}}</ref> by both the male and the female, with the former typically incubating at night.<ref name="hbw">{{cite journal |last1=Wiersma|first1=P.|last2=Kirwan|first2=G. M.|last3=Boesman|first3=P.|editor1-last=del Hoyo |editor1-first=Josep |editor2-last=Elliott |editor2-first=Andrew |editor3-last=Sargatal |editor3-first=Jordi |editor4-last=Christie |editor4-first=David A. |editor5-last=de Juana |editor5-first=Eduardo |year=2020 |title=Killdeer (''Charadrius vociferus'') |journal=Handbook of the Birds of the World Alive |url=https://www.hbw.com/species/killdeer-charadrius-vociferus |publisher=Lynx Edicions |location=Barcelona, Spain |doi=10.2173/bow.killde.01 |access-date=12 June 2018 |url-access=subscription}}</ref> The time dedicated to incubation is related to temperature, with one study recording that killdeer incubated eggs 99% of the time when the temperature was about {{convert|13|C|F}}, 76% of the time around {{convert|26|C|F}}, and 87% of the time at about {{convert|35|C|F}}. When it is hot (above at least {{convert|25|C|F}}), incubation cools the eggs, generally through shading by one of the parents.<ref name="Bergstrom1989">{{cite journal |last1=Bergstrom |first1=Peter W. |title=Incubation temperatures of Wilson's plovers and killdeers |journal=The Condor |volume=91 |issue=3 |year=1989 |pages=634–641 |doi=10.2307/1368114 |jstor=1368114|issn=1938-5129}}</ref>

[[File:Killdeer eggs.jpg|thumb|left|Eggs in a nest on the ground]]
About 53% of eggs are lost,<ref name="Brunton1990"/> mainly to predators.<ref name="NolBrooks1982">{{Cite journal| issn = 0273-8570| volume = 53| issue = 3| pages = 263–268| last1 = Nol| first1 = Erica| last2 = Brooks| first2 = Ronald J.| title = Effects of predator exclosures on besting success of killdeer| journal = Journal of Field Ornithology| year = 1982}}</ref> The young are [[precocial]], starting to walk within the first days of their life. After they hatch, both parents lead them out of the nest, generally to a feeding territory with dense vegetation under which the chicks can hide when a predator is near.<ref name="Lenington1980"/> The chicks are raised, at least in single-brood pairs, by both parents, likely because of the high failure rate of nests and the need for both parents to be present to successfully raise the young.<ref name="Brunton1988b"/> In these broods, the young are usually attended by one parent at a time (generally the female) until about two weeks of age, after which both parents are occasionally seen together with the chicks. Otherwise, the inattentive adult is at least about {{convert|23|m|ft|abbr=on}} away from the chicks. Periods of attentiveness for each parent generally last from about one to one and a half hours. When the chicks are young, this is mainly spent standing; as the chicks get older, less time is dedicated to standing. When the young are below two weeks of age, the attending adult spends little time feeding; foraging time increases as the chicks grow. The inattentive adult defends the young most of the time when they are less than a week old, but this task steadily shifts onto the attentive adult, until about three weeks of age, when the attending parent does almost all of the defense. One parent at a time broods the chicks and does so frequently until they are two days old. The young are brooded during the day until about 15 days after hatching and during the night for about 18 days after hatching. The only time when they are not in the presence of a parent is when the parents are mating or responding to a predator or aggressive conspecific.<ref name="Lenington1980">{{cite journal |last=Lenington |first=Sarah |year=1980 |title=Bi-parental care in killdeer: An adaptive hypothesis |journal=The Wilson Bulletin |volume=92 |issue=1 |pages=8–20|issn=0043-5643}}</ref>

[[File:Charadrius vociferus -Sandy Hook, New Jersey, USA -juvenile-8.jpg|thumb|A chick in [[New Jersey]]]]

When a pair has two broods, the second is usually attended by just the male (which can hatch the eggs on his own, unlike the female<ref name="Brunton1988b">{{cite journal |last=Brunton |first=Dianne H. |author-link=Dianne Brunton |title=Energy expenditure in reproductive effort of male and female killdeer (''Charadrius vociferus'') |year=1988 |journal=[[The Auk]] |volume=105 |issue=3 |pages=553–564|issn=1938-4254|doi=10.1093/auk/105.3.553 }}</ref>). In this case, the male does not spend most of the time standing; the amount of time he does stand, though, stays constant as the chicks age. Like attentive adults in two-parent broods, the sole parent increases the time spent foraging as the young age.<ref name="Lenington1980"/>

The young [[fledge]] about 31 days after hatching, and generally move to moister areas in valleys and on the banks of rivers. They may be cared for by their parents for up to 10 days after they fledge, and exceptionally for 81 days after hatching. About 52 to 63% of nests fail to produce any fledged young. Breeding starts after one year of age.<ref name="hbw"/> The killdeer has a maximum lifespan of 10 years and 11 months.<ref name="ClappKlimkiewicz1982">{{Cite journal| issn = 0273-8570| volume = 53| issue = 2| pages = 81–124| last1 = Clapp| first1 = Roger B.| last2 = Klimkiewicz| first2 = M. Kathleen| last3 = Kennard| first3 = John H.| title = Longevity records of North American birds: Gaviidae through Alcidae| journal = Journal of Field Ornithology| year=1982 |jstor=4512701| bibcode = 1982JFOrn..53...81C}}</ref>

===Feeding===
The killdeer feeds primarily on insects (especially beetles and flies), in addition to millipedes, worms, snails, spiders, and some seeds. It opportunistically takes [[tree frog]]s and dead [[minnow]]s.<ref name="hbw"/> It forages almost exclusively in fields (no matter the tide), especially those with short vegetation and with cattle (which likely shorten the vegetation) and standing water. Standing water alone does not have a significant effect on field choice unless combined with cattle.<ref name="LongRalph2001">{{cite journal |last1=Long |first1=Linda L. |last2=Ralph |first2=C. John |title=Dynamics of habitat use by shorebirds in estuarine and agricultural habitats in northwestern California |journal=The Wilson Bulletin |volume=113 |issue=1 |year=2001 |pages=41–52 |doi=10.1676/0043-5643(2001)113[0041:DOHUBS]2.0.CO;2|s2cid=85929172 |issn=0043-5643}}</ref> Viable [[disseminule]]s can be recovered from killdeer feces, indicating that this bird is important in transporting aquatic organisms.<ref name="ProctorMalone1967">{{cite journal |last1=Proctor |first1=Vernon W.|last2=Malone |first2=Charles R. |last3=DeVlaming |first3=Victor L. |title=Dispersal of aquatic organisms: Viability of disseminules recovered from the intestinal tract of captive killdeer |journal=Ecology |volume=48 |issue=4 |year=1967 |pages=672–676 8|doi=10.2307/1936517 |jstor=1936517|bibcode=1967Ecol...48..672P |issn=1939-9170}}</ref>

The killdeer uses visual cues to forage. An example of this is "foot-trembling",<ref name="Eberhart-Phillips2016">{{cite journal|last1=Eberhart-Phillips|first1=Luke J.|title=Dancing in the moonlight: evidence that killdeer foraging behavior varies with the lunar cycle|journal=Journal of Ornithology|volume=158|issue=1|year=2016|pages=253–262|issn=2193-7192|doi=10.1007/s10336-016-1389-4|s2cid=42947525}}</ref> where it stands on one foot, shaking the other in shallow water for about five seconds, pecking at any prey stirred up.<ref name="Smith1970">{{cite journal|last=Smith|first=Susan M.|title="Foot-trembling" feeding behavior by a killdeer|year=1970|journal=[[The Condor (journal)|The Condor]]|page=245|volume=72|issue=2|issn=1938-5129|doi=10.2307/1366650|jstor=1366650}}</ref> When feeding in fields, it sometimes follows plows to take earthworms disturbed to the surface.<ref name="hbw"/> The female forages significantly more than the male during most stages of breeding. The former feeds the most before and during egg-laying, the least when incubation starts (as little time to feed remains), with a return to high levels after.<ref name="Brunton1988a"/> During the nonbreeding season, the killdeer forages during the night, depending on the lunar cycle. When the moon is full, it feeds more at night and roosts more during the day. Foraging at night has benefits for this bird, including increased insect abundance and reduced predation.<ref name="Eberhart-Phillips2016"/>

==Predators and parasites==
The killdeer is parasitized by [[acanthocephalan]]s, [[cestode]]s, [[nematode]]s, and [[trematode]]s.<ref name="Eckman1968">{{cite journal|last1=Eckman|first1=Michael K.|title=Helminth parasites of the killdeer in Colorado|journal=The Journal of Parasitology|volume=54|issue=6|year=1968|page=1143|issn=0022-3395|doi=10.2307/3276980|jstor=3276980}}</ref> It is preyed upon by [[American herring gull]]s, [[Corvus|common crow]]s, [[raccoon]]s, and [[striped skunk]]s.<ref name="Brunton1990"/> The mentioned birds and other avian predators are the majority of predators in some areas during the breeding season. Predation is not limited to eggs and chicks: [[mustelid]]s, for example, can kill incubating adults.<ref name="JohnsonOring2002">{{cite journal |last1=Johnson |first1=Matthew |last2=Oring |first2=Lewis W. |title=Are nest exclosures an effective tool in plover conservation? |journal=Waterbirds|volume=25 |issue=2 |year=2002 |page=184 |doi=10.1675/1524-4695(2002)025[0184:ANEAET]2.0.CO;2|s2cid=83933209 |issn=1939-9170}}</ref>

===Responses to predators===
{{Further|Distraction display}}
The parents use various methods to distract predators during the breeding season. One method is the "broken-wing display",<ref name="Deane1944">{{cite journal |last=Deane |first=C. Douglas|title=The broken-wing behavior of the killdeer |journal=The Auk |volume=61|issue=2|year=1944|pages=243–247 |doi=10.2307/4079369 |jstor=4079369|issn=1938-4254}}</ref> also known as "injury feigning".<ref name="Gochfeld1984">{{cite book |last1=Gochfeld |first1=Michael |title=Shorebirds|editor-last1=Burger |editor-first1=Joanna |editor-last2=Olla |editor-first2=Bori L. |year=1984 |pages=289–377 |doi=10.1007/978-1-4684-4691-3_8 |isbn=978-1-4684-4693-7 |chapter=Antipredator Behavior: Aggressive and Distraction Displays of Shorebirds}}</ref> Before displaying, it usually runs from its nest, making alarm calls and other disturbances. When the bird has the attention of the predator, the former turns its tail towards the latter, displaying the threatening orange color of the rump. It then crouches, droops its wings, and lowers its tail, which is more common for them.<ref name="Deane1944"/> With increasing intensity, the wings are held higher, the tail is fanned out, and the tail becomes more depressed.<ref name="Brunton1990"/> Another behavior that has received attention is the "ungulate display", where the adult raises its wings, exposes its rump, lowers its head, and charges at the intruder. This can be fatal to the displaying bird.<ref name="Brunton1986">{{Cite journal| volume = 98| issue = 4| pages = 605–607| last = Brunton| first = Dianne H.| title = Fatal antipredator behavior of a killdeer| journal = The Wilson Bulletin| year = 1986|issn=0043-5643}}</ref>
<gallery class="centered" mode="packed" caption="The broken-wing display">
File:No one can fake an injury like a Killdeer (34125990963).jpg
File:Charadrius vociferus -distraction display to protect nest-8.ogv
File:Charadrius vociferus tx1.jpg
</gallery>
The intensity of the responses to predators varies throughout the breeding season. During egg-laying, the most common response to predators is to quietly leave the nest. As incubation starts and progresses, the intensity of predator responses increases, peaking after hatching. This is probably because it is worth more to protect the young then, as they are more likely to fledge. After hatching, reactions decrease in intensity, until a normal response is called. This is because the young become more independent as they age.<ref name="Brunton1990">{{Cite journal| volume = 26| issue = 3| pages = 181–190| last = Brunton| first = Dianne H.| title = The effects of nesting stage, sex, and type of predator on parental defense by killdeer (''Charadrius vociferous''): Testing models of avian parental defense| journal = Behavioral Ecology and Sociobiology| date = 1990|issn=1432-0762| doi=10.1007/bf00172085| bibcode = 1990BEcoS..26..181B| hdl = 2027.42/46896| s2cid = 25058409| hdl-access = free}}</ref>

==Conservation status==
The killdeer was formerly considered a [[least-concern species]] by the IUCN due to its large range of about {{convert|26.3|km2|mi2|disp=preunit|million |abbr=on}} and population, estimated by the IUCN to be about one million birds,<ref name="iucn" /> or about two million, according to the ''[[Handbook of the Birds of the World Alive]]''.<ref name="hbw"/> As of 2024, it is considered a [[near-threatened species]] due to its population decline exceeding 20% in three generations,<ref name=iucn/> though the decline is not rapid enough to warrant uplisting the killdeer to a [[vulnerable species]].<ref name="iucn" /> It is protected in the US by the [[Migratory Bird Treaty Act of 1918]],<ref>{{cite web | url = https://www.fws.gov/birds/management/managed-species/migratory-bird-treaty-act-protected-species.php | year=2013|title = Migratory Bird Treaty Act Protected Species (10.13 List) | publisher = US Fish & Wildlife Service | access-date = 10 October 2018}}</ref> and in Canada by the [[Migratory Birds Convention Act]].<ref>{{cite web|url=https://www.canada.ca/en/environment-climate-change/services/migratory-birds-legal-protection/convention-act.html|title=Birds protected under the Migratory Birds Convention Act|year=2017|access-date=10 October 2018|publisher=Government of Canada|archive-url=https://web.archive.org/web/20190520104408/https://www.canada.ca/en/environment-climate-change/services/migratory-birds-legal-protection/convention-act.html|archive-date=20 May 2019}}</ref>

==Notes==
{{NoteFoot}}

==References==
{{Reflist}}
<!-- BulletinOfTheBritishOrnithologistsClub101:339. WilsonBull18:47 (migration data - compare to current Ohio checklist http://www.ohiobirds.org/publications/OBRClist.pdf) -->

==External links==
* {{InternetBirdCollection|killdeer-charadrius-vociferus|Killdeer}}
* {{VIREO|killdeer|Killdeer}}

{{Taxonbar|from=Q755737}}
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[[Category:Charadrius]]
[[Category:Birds of North America]]
[[Category:Birds of the Caribbean]]
[[Category:Meso-American wintering birds]]
[[Category:Wintering birds of South America]]
[[Category:Birds described in 1758]]
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[[Category:Animal taxa named by Carl Linnaeus]]
[[Category:Birds of the United States]]