View source for Eurystomus

{{Short description|Genus of birds}}
{{Italic title}}
{{Automatic taxobox
| name = ''Eurystomus''
| image = Dollarbird by N.A. Nazeer.jpg
| image_caption = [[Dollarbird]]s in India
| taxon = Eurystomus
| authority = [[Louis Pierre Vieillot|Vieillot]], 1816
| type_species = ''[[Oriental dollarbird|Eurystomus orientalis]]''
| type_species_authority = [[Carl Linnaeus|Linnaeus]], 1766
| subdivision_ranks = Species
| subdivision = 
See text.
}}

'''''Eurystomus''''' is a [[genus]] of [[Coraciidae|roller]], one of the two genera in that family of [[bird]]s.
The name means ‘broad mouth’, from the Greek ''eurus'' ({{lang|grc|[[wikt:εὐρύς|εὐρύς]]}}, ‘broad, wide’) and ''stoma'' ({{lang|grc|[[wikt:στόμα|στόμα]]}}, ‘mouth’).<ref>{{cite book|author=William Somerville Orr|author-link=William Somerville Orr|title=Orr's circle of the sciences: a series of treatises on the principles of science, with their application to practical pursuits|publisher=W.S. Orr & Company|url=https://archive.org/details/orrscirclescien03orrgoog|year=1855|page=[https://archive.org/details/orrscirclescien03orrgoog/page/n537 517]}}</ref>

''Eurystomus'' contains four broad-billed species, which breed in Africa, Asia and Australasia. Two species are restricted to Africa, one of which, the [[broad-billed roller]], is [[bird migration|migratory]]. The [[oriental dollarbird]] has a large distribution ranging from India to Japan and Australia and it too, is migratory over the northern and southern extremes of its range. The final species, the [[azure dollarbird]], is [[endemism|endemic]] to the [[Moluccas]] in Indonesia. In general they are open country foragers, occurring in woodland, savanna and farmland. The azure dollarbird and the broad-billed roller are both associated with rainforests but nevertheless require open areas in which to forage.

The species of the genus ''Eurystomus'' vary from the other genus of rollers, ''[[Coracias]]'', in having proportionally longer wings and shorter legs. These morphological differences are reflected in differences of foraging techniques. ''Coracias'' rollers forage from a fixed perch and take prey by swooping down onto it on the ground, while the faster and more agile ''Eurystomus'' rollers catch their prey on the wing. Unlike the species of the genus ''Coracias'', they do not perform the "rolling" display which gives the family its common name.<ref name = "HBW">{{Citation | first = C | last = Fry | editor-first = Josep | editor-last = del Hoyo | editor2-first = Andrew | editor2-last = Elliott | editor3-last = Sargatal | editor3-first = Jordi | contribution = Family Coraciidae (Rollers) | title = [[Handbook of the Birds of the World]]. Volume 6, Mousebirds to Hornbills | year = 2001 | pages = [https://archive.org/details/handbookofbirdso0001unse/page/342 342–369] | place = Barcelona | publisher = Lynx Edicions | isbn = 978-84-87334-30-6 }}</ref>

==Taxonomy==
The genus ''Eurystomus'' was introduced in 1816 by the French ornithologist [[Louis Pierre Vieillot]] to accommodate the [[Oriental dollarbird]].<ref>{{cite book | last=Vieillot  | first=Louis Pierre | author-link=Louis Pierre Vieillot | year=1816 | title=Analyse d'une Nouvelle Ornithologie Élémentaire | publisher=Deterville/self |  location=Paris | page=37 | language=French| url=https://gallica.bnf.fr/ark:/12148/bpt6k9745205x/f43.item }}<!--BHL has a scan of an 1883 reprint - same pagination http://biodiversitylibrary.org/page/12830237 --></ref><ref>{{ cite book | editor-last=Peters | editor-first=James Lee | editor-link=James L. Peters | year=1945 | title=Check-List of Birds of the World | volume=5 | publisher=Harvard University Press | place=Cambridge, Massachusetts  | page=244 | url=https://www.biodiversitylibrary.org/page/14480255 }}</ref> The name is from [[Classical Greek]] ''eurustomos'' meaning "wide-mouthed".<ref>{{cite book | last=Jobling | first=James A. | year=2010| title=The Helm Dictionary of Scientific Bird Names | publisher=Christopher Helm | location=London | isbn=978-1-4081-2501-4 | page=154 }}</ref>

A [[molecular phylogenetic]] study by Ulf Johansson and collaborators published in 2018 found that the [[azure dollarbird]] (''Eurystomus azureus'') was nested in a [[clade]] containing [[subspecies]] of the [[Oriental dollarbird]] (''Eurystomus orientalis'').<ref>{{cite journal | last1=Johansson | first1=U.S. | last2=Irestedt | first2=M. |last3=Qu | first3=Y. |last4=Ericson | first4=P. G. P. | date=2018 |title=Phylogenetic relationships of rollers (Coraciidae) based on complete mitochondrial genomes and fifteen nuclear genes |journal=Molecular Phylogenetics and Evolution |volume=126 |pages=17–22|doi=10.1016/j.ympev.2018.03.030| pmid=29631051 | bibcode=2018MolPE.126...17J | s2cid=5011292 }}</ref>
{{Clade| style=font-size:90%;line-height:90%
|label1=''Eurystomus''
|1={{clade
   |1={{clade
      |1=[[Broad-billed roller]] – ''E. glaucurus''
      |2=[[Blue-throated roller]] – ''E. gularis''
      }}
   |2={{clade
      |1=[[Oriental dollarbird]] – ''E. orientalis orientalis''
      |2={{clade
         |1=[[Azure dollarbird]] – ''E. azureus''
         |2={{clade
            |1=Oriental dollarbird – ''E. orientalis pacificus''
            |2=Oriental dollarbird – ''E. orientalis waigiouensis''
            }}
         }}
      }}
   }}
}}

== Species ==
{| class="wikitable"
|-
! Image !! Scientific name  !! Common name  !! Distribution
|-
|[[File:Blue-throated Roller from Canopy Walkway - Kakum NP - Ghana 14 S4E1636 (16011512580).jpg|120px]] || ''Eurystomus gularis''||[[Blue-throated roller]]  ||western sub-Saharan Africa from Guinea to Cameroon, south to northern Angola, and west to south-eastern Uganda
|-
|[[File:Broad-billed Roller, Ankarafantsika, Madagascar, crop.jpg|120px]] || ''Eurystomus glaucurus'' || [[Broad-billed roller]]|| tropical Africa and Madagascar
|-
|[[File:Dollarbird Samcem Dec02.JPG|120px]] || ''Eurystomus orientalis'' ||[[Oriental dollarbird]] ||Australia to Japan and India.
|-
|[[File:2015-09-13 Eurystomus azureus, Halmahera Timur, Indonesia.jpg|120px]]|| ''Eurystomus azureus'' ||[[Azure dollarbird]] || Maluku Islands in Indonesia
|-
|}

== References ==
{{Reflist}}
* ''Kingfishers, Bee-eaters and Rollers'' by Fry, Fry and Harris, {{ISBN|0-7136-8028-8}}

{{Cavitaves|K.|state=collapsed}}
{{Taxonbar|from=Q992943}}

[[Category:Eurystomus| ]]
[[Category:Bird genera]]
[[Category:Taxa named by Louis Pierre Vieillot]]

{{Coraciiformes-stub}}