Editing Cliff swallow (section)

== Taxonomy ==
[[File:Petrochelidon_pyrrhonota_1894.jpg|thumb|''Petrochelidon pyrrhonota'' 1894]]
The cliff swallow belongs to the largest [[Phylogenetics|order]] and dominant avian group – ''[[Passerine|Passeriformes]]''.<ref name=":2" /><ref name=":3" /><ref name=":5">{{Cite web|url=http://tolweb.org/Passeriformes/15868/2013.02.06|title=Passeriformes. Perching Birds. Passerine Birds.|last1=Edwards|first1=Scott V.|last2=Harshman|first2=John|date=February 6, 2013|website=The Tree of Life Web Project|access-date=October 7, 2017}}</ref> They are the perching birds, or the passerines.<ref name=":5" /><ref name=":10">{{Cite web|url=https://www.britannica.com/animal/passeriform|title=Passeriform|last1=Gill|first1=Frank|last2=Clench|first2=Mary H.|date=August 1, 2016|website=Encyclopædia Britannica|publisher=Encyclopædia Britannica, inc.|last3=Austin|first3=Oliver L.}}</ref> All the bird species in this order have four toes, three pointing forward and one pointing backwards ([[anisodactyly|anisodactylous]]), that enable them to perch with ease.<ref name=":5" /><ref name=":10" /> The sub-order that the cliff swallow belongs to is [[Songbird|''Oscines'']] (or Passeri), for the songbirds.<ref name=":5" /> The family that encompasses approximately 90 species of swallows and martins, ''Hirundinidae'', includes birds that have small stream-lined bodies made for great agility and rapid flight.<ref name=":6">{{Cite web |last= |date=July 21, 2011 |title=Hirundinidae |url=https://www.britannica.com/animal/Hirundinidae |website=Encyclopædia Britannica |publisher=Encyclopædia Britannica Inc.}}</ref> Furthermore, those in the family Hirundinidae have short-flat bills for their largely insectivorous diets, small feet because they spend much of their time in flight and long wings for energy-efficient flight.<ref name=":3" /><ref name=":6" />

There are five subspecies of cliff swallow distinguished on the basis of plumage colour, body size, and distribution – ''Petrochelidon pyrrhonota pyrrhonota'', ''P.&nbsp;p.&nbsp;melanogaster'', ''P.&nbsp;p.&nbsp;tachina'', ''P.&nbsp;p.&nbsp;hypopolia'', ''P.&nbsp;p.&nbsp;ganieri''.<ref>{{Cite web|url=https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=178455#null|title=Petrochelidon pyrrhonota (Vieillot, 1817)|last=Integrated Taxonomic Information System|date=October 7, 2017|website=ITIS}}</ref> In addition, three core genera of ''hirundo'' were established on the basis of molecular studies: ''Hirundo sensu stricto'', containing the barn swallow; ''Cecropis'', containing the red-rumped swallow; and ''Petrochelidon'', containing the cliff swallow.<ref name=":2" /> The genetic tests deemed ''Petrochelidon'' and ''Cecropis'' sister to each other and both closest to ''Delichon'', the house martins.<ref name=":2" /> Finally, the [[cave swallow]] was identified as the nearest living relative in [[North America]] of the cliff swallow.<ref name=":2" /> The cave swallow has a similar plumage to the cliff swallow; however, the former has a dark cap and pale throat, and also a much smaller distribution in North America, most likely due to a decline in suitable cave sites.<ref name=":2" />