Editing Bird (section)

===Feathers, plumage, and scales===
{{Main|Feather|Flight feather|Down feather}}
[[File:African Scops owl.jpg|alt=Owl with eyes closed in front of similarly coloured tree trunk partly obscured by green leaves|thumb|left|The [[disruptively patterned]] plumage of the [[African scops owl]] allows it to blend in with its surroundings.]]

Feathers are a feature characteristic of birds (though also present in [[Feathered dinosaurs|some dinosaurs]] not currently considered to be true birds). They facilitate [[bird flight|flight]], provide insulation that aids in [[thermoregulation]], and are used in display, camouflage, and signalling.<ref name="Gill"/> There are several types of feathers, each serving its own set of purposes. Feathers are epidermal growths attached to the skin and arise only in specific tracts of skin called [[Pterylography|pterylae]]. The distribution pattern of these feather tracts (pterylosis) is used in taxonomy and systematics. The arrangement and appearance of feathers on the body, called [[plumage]], may vary within species by age, [[social status]],<ref>{{Cite journal|last=Belthoff |first=James R. |date=1 August 1994|title=Plumage Variation, Plasma Steroids and Social Dominance in Male House Finches |journal=The Condor |volume=96 |issue=3 |pages=614–625 |doi=10.2307/1369464 |author2=Dufty |author3=Gauthreaux|url=http://works.bepress.com/james_belthoff/29 |jstor=1369464 }}</ref> and [[sexual dimorphism|sex]].<ref>{{cite web|last=Guthrie| first=R. Dale|title=How We Use and Show Our Social Organs |work=Body Hot Spots: The Anatomy of Human Social Organs and Behavior |url=http://employees.csbsju.edu/lmealey/hotspots/chapter03.htm |access-date=19 October 2007| archive-url = https://web.archive.org/web/20070621225459/http://employees.csbsju.edu/lmealey/hotspots/chapter03.htm| archive-date = 21 June 2007}}</ref>

Plumage is regularly [[moult]]ed; the standard plumage of a bird that has moulted after breeding is known as the "{{Birdgloss|basic plumage|non-breeding}}" plumage, or—in the [[Humphrey–Parkes terminology]]—"basic" plumage; breeding plumages or variations of the basic plumage are known under the Humphrey–Parkes system as "{{Birdgloss|alternate plumage|alternate}}" plumages.<ref>{{Cite journal|last1=Humphrey |first1=Philip S. |date=1 June 1959|title=An approach to the study of molts and plumages |journal=The Auk |volume=76 |pages=1–31 |url=http://sora.unm.edu/sites/default/files/journals/auk/v076n01/p0001-p0031.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://sora.unm.edu/sites/default/files/journals/auk/v076n01/p0001-p0031.pdf |archive-date=9 October 2022 |url-status=live |issue=1 |jstor=4081839|last2=Parkes|first2=K. C.|doi=10.2307/4081839}}</ref> Moulting is annual in most species, although some may have two moults a year, and large birds of prey may moult only once every few years. Moulting patterns vary across species. In passerines, [[flight feather]]s are replaced one at a time with the innermost {{Birdgloss|primary}} being the first. When the fifth of sixth primary is replaced, the outermost {{Birdgloss|tertiaries}} begin to drop. After the innermost tertiaries are moulted, the {{Birdgloss|secondaries}} starting from the innermost begin to drop and this proceeds to the outer feathers (centrifugal moult). The greater primary {{Birdgloss|coverts}} are moulted in synchrony with the primary that they overlap.<ref name="pettingill">{{Cite book|author=Pettingill Jr. OS|year=1970|title=Ornithology in Laboratory and Field|url=https://archive.org/details/ornithologyinlab0000pett_i2b3|isbn=0-12-552455-2|publisher=Burgess Publishing Co}}</ref>

A small number of species, such as ducks and geese, lose all of their flight feathers at once, temporarily becoming flightless.<ref name="debeeretal">{{cite book |last1=de Beer |first1=S. J. |last2=Lockwood |first2=G. M. |last3=Raijmakers |first3=J. H. F. S. |last4=Raijmakers |first4=J. M. H. |last5=Scott |first5=W. A. |last6=Oschadleus |first6=H. D. |last7=Underhill |first7=L. G. |year=2001 |url=http://safring.adu.org.za/downloads/ringers-manual.pdf |title=SAFRING Bird Ringing Manual |archive-url=https://web.archive.org/web/20171019032817/http://safring.adu.org.za/downloads/ringers-manual.pdf |archive-date=19 October 2017}}</ref> As a general rule, the tail feathers are moulted and replaced starting with the innermost pair.<ref name="pettingill"/> Centripetal moults of tail feathers are however seen in the [[Phasianidae]].<ref>{{Cite journal|last=Gargallo|first=Gabriel|date=1 June 1994|title=Flight Feather Moult in the Red-Necked Nightjar ''Caprimulgus ruficollis'' |journal=Journal of Avian Biology |volume=25|issue=2|pages=119–124 |doi=10.2307/3677029 |jstor=3677029}}</ref> The centrifugal moult is modified in the tail feathers of [[woodpecker]]s and [[treecreeper]]s, in that it begins with the second innermost pair of feathers and finishes with the central pair of feathers so that the bird maintains a functional climbing tail.<ref name="pettingill"/><ref>{{Cite journal|last=Mayr |first=Ernst |year=1954 |title=The tail molt of small owls |journal=The Auk |volume=71 |issue=2 |pages=172–178 |url=http://sora.unm.edu/sites/default/files/journals/auk/v071n02/p0172-p0178.pdf |archive-url=https://web.archive.org/web/20141004053953/http://sora.unm.edu/sites/default/files/journals/auk/v071n02/p0172-p0178.pdf |archive-date=4 October 2014 |doi=10.2307/4081571 |jstor=4081571 }}</ref> The general pattern seen in [[passerine]]s is that the primaries are replaced outward, secondaries inward, and the tail from centre outward.<ref>{{cite web|first=Robert B. |last=Payne |title=Birds of the World, Biology 532 |url=http://www.ummz.umich.edu/birds/resources/families_otw.html |publisher=Bird Division, University of Michigan Museum of Zoology |access-date=20 October 2007 |archive-url=https://web.archive.org/web/20120226062512/http://www.ummz.umich.edu/birds/resources/families_otw.html |archive-date=26 February 2012 }}</ref> Before nesting, the females of most bird species gain a bare [[brood patch]] by losing feathers close to the belly. The skin there is well supplied with blood vessels and helps the bird in incubation.<ref>{{Cite journal|last=Turner |first=J. Scott |year=1997 |title=On the thermal capacity of a bird's egg warmed by a brood patch |journal=Physiological Zoology |volume=70 |issue=4 |pages=470–480 |doi=10.1086/515854 |pmid=9237308 }}</ref>
[[File:Red Lory (Eos bornea)-6.jpg|alt=Red parrot with yellow bill and wing feathers in bill|upright|right|thumb|[[Red lory]] preening]]
Feathers require maintenance and birds preen or groom them daily, spending an average of around 9% of their daily time on this.<ref>{{Cite journal|last=Walther |first=Bruno A. |year=2005 |title=Elaborate ornaments are costly to maintain: evidence for high maintenance handicaps |journal=Behavioral Ecology |volume=16 |issue=1 |pages=89–95 |doi=10.1093/beheco/arh135|doi-access=free }}</ref> The bill is used to brush away foreign particles and to apply [[wax]]y secretions from the [[uropygial gland]]; these secretions protect the feathers' flexibility and act as an [[Antimicrobial|antimicrobial agent]], inhibiting the growth of feather-degrading [[bacteria]].<ref>{{Cite journal|last1=Shawkey |first1=Matthew D. |year=2003 |title=Chemical warfare? Effects of uropygial oil on feather-degrading bacteria |journal=[[Journal of Avian Biology]] |volume=34 |issue=4 |pages=345–349 |doi=10.1111/j.0908-8857.2003.03193.x |last2=Pillai |first2=Shreekumar R. |last3=Hill |first3=Geoffrey E.}}</ref> This may be supplemented with the secretions of [[formic acid]] from ants, which birds receive through a behaviour known as [[Anting (bird activity)|anting]], to remove feather parasites.<ref>{{Cite journal|last=Ehrlich |first=Paul R. |year=1986 |title=The Adaptive Significance of Anting |journal=The Auk |volume=103 |issue=4 |page=835 |url=http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0835-p0835.pdf |archive-url=https://web.archive.org/web/20160305202116/http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0835-p0835.pdf |archive-date=5 March 2016 }}</ref>

The [[Bird anatomy#Scales|scales]] of birds are composed of the same keratin as beaks, claws, and spurs. They are found mainly on the toes and [[metatarsus]], but may be found further up on the ankle in some birds. Most bird scales do not overlap significantly, except in the cases of [[kingfisher]]s and [[woodpecker]]s.
The scales of birds are thought to be [[Homology (biology)|homologous]] to those of reptiles and mammals.<ref>{{Cite book|last=Lucas |first=Alfred M. |year=1972 |title=Avian Anatomy – integument |location=East Lansing, Michigan |publisher=USDA Avian Anatomy Project, Michigan State University |pages=67, 344, 394–601}}</ref>