Editing Alpine chough (section)

==Description==
[[File:Yellow-billed_Chough_from_North_Sikkim,_India_November_2019.jpg|thumb|left|From [[North Sikkim]], [[India]].]]
The adult of the nominate subspecies of the Alpine chough has glossy black [[plumage]], a short yellow bill, dark brown [[Iris (anatomy)|irises]], and red legs.<ref name= Madge94/> It is slightly smaller than the red-billed chough, at {{convert|37|–|39|cm|in|abbr=off}} length with a {{convert|12|-|14|cm|in|abbr=on}} tail and a {{convert|75|-|85|cm|in|abbr=on}} wingspan, but has a proportionally longer tail and shorter wings. It has a similar buoyant and easy flight.<ref name=BWP>{{cite book| editor1-last = Snow | editor1-first = David |editor2-last = Perrins |editor2-first=Christopher M. | title = The Birds of the Western Palearctic concise edition (2 volumes) | publisher = Oxford University Press |year = 1998| location =Oxford |pages = 1464–1466 | isbn = 978-0-19-854099-1}}</ref> The sexes are identical in appearance, although the male averages slightly larger than the female. The juvenile is duller than the adult, with a dull yellow bill and brownish legs.<ref name= Madge94/> The Alpine chough is unlikely to be confused with any other species; although the jackdaw and red-billed chough share its range, the jackdaw is smaller and has unglossed grey plumage, and the red-billed chough has a long red bill.<ref name= BWP/>

The subspecies ''P.&nbsp;g.&nbsp;digitatus'' averages slightly larger than the nominate form, weighing {{convert|191|–|244|g|oz|abbr=on}} against {{convert|188|–|252|g|oz|abbr=on}} for ''P.&nbsp;g.&nbsp;graculus'', and it has stronger feet.<ref name= Madge94/><ref name=BWP/> This is in accordance with [[Bergmann's rule]], which predicts that the largest birds should be found higher elevations or in colder and more arid regions. The extremities of the body, the bill and [[tarsus (skeleton)|tarsus]], are longer in warmer areas, in line with [[Allen's rule]]. Temperature seems to be the most important cause of body variation in the Alpine chough.<ref name=" Ecogeographic" >{{cite journal| last= Laiolo | first=Paola |author2=Rolando, Antonio| year= 2000 | title= Ecogeographic correlates of morphometric variation in the Red-billed Chough ''Pyrrhocorax pyrrhocorax ''and the Alpine Chough ''Pyrrhocorax graculus'' | journal= Ibis | volume= 43 | issue = 3 | pages= 602–616 | doi = 10.1111/j.1474-919X.2001.tb04888.x}}</ref>

The flight of the Alpine chough is swift and acrobatic with loose, deep wing beats. Its high manoeuvrability is accomplished by fanning the tail, folding its wings, and soaring in the [[Vertical draft|updraughts]] at cliff faces. Even in flight, it can be distinguished from the red-billed chough by its less rectangular wings, and longer, less square-ended tail.<ref name= BWP/><ref name= burton>{{cite book |last = Burton |first = Robert |title = Bird behaviour |year = 1985 |page = [https://archive.org/details/birdbehaviour0000burt/page/22 22] |location = London |publisher = Granada |isbn = 978-0-246-12440-1 |url = https://archive.org/details/birdbehaviour0000burt/page/22 }}</ref>

The [[trill (music)|rippling]] {{Not a typo|''preep''}} and whistled {{Not a typo|''sweeeooo''}} calls of the Alpine chough are quite different from the more typically [[crow|crow-like]] {{Not a typo|''chee-ow''}} vocalisations of the jackdaw and the red-billed chough. It also has a rolling {{Not a typo|''churr''}} [[alarm signal|alarm call]], and a variety of quiet warbles and squeaks given by resting or feeding birds.<ref name= Madge94/> In a study of chough calls throughout the [[Palearctic realm|Palearctic region]] it was found that call [[audio frequency|frequencies]] in the Alpine chough showed an [[inverse relationship]] between body size and frequency, being higher-pitched in smaller-bodied populations.<ref name=Laiolo2001>{{cite journal |author= Laiolo, Paola |author2= Rolando, Antonio|author3= Delestrade, Anne|author4= de Sanctis, Augusto |year= 2001| title= Geographical variation in the calls of the choughs |journal= The Condor |volume= 103 |issue= 2 |pages= 287–297 |doi= 10.1650/0010-5422(2001)103[0287:GVITCO]2.0.CO;2|s2cid= 85866352|doi-access= free }}</ref>