Editing Feather (section)

===Coloration===
[[File:Red feather pigments.jpg|thumb|left|Colors resulting from different feather pigments<br />'''Left:''' [[turacin]] (red) and [[turacoverdin]] (green, with some structural blue [[iridescence]] at lower end) on the wing of ''[[Tauraco bannermani]]''<br />'''Right:''' [[carotenoid]]s (red) and [[melanin]]s (dark) on belly/wings of ''[[Ramphocelus bresilius]]'']]
The colors of feathers are produced by pigments, by microscopic structures that can [[refraction|refract]], reflect, or scatter selected wavelengths of light, or by a combination of both.

Most feather pigments are [[melanin]]s (brown and beige [[pheomelanin]]s, black and grey [[eumelanin]]s) and [[carotenoid]]s (red, yellow, orange); other pigments occur only in certain [[taxa]] – the yellow to red [[psittacofulvin]]s<ref>{{Cite journal|journal=Biology Letters|title=Distribution of unique red feather pigments in parrots|volume=1|issue=1|pages=38–43|year=2005|last1= McGraw |first1=KH |first2= MC |last2= Nogare| doi=10.1098/rsbl.2004.0269| pmid= 17148123|pmc=1629064}}</ref> (found in some [[parrot]]s) and the red [[turacin]] and green [[turacoverdin]] ([[porphyrin]] pigments found only in [[turaco]]s).

[[Structural coloration]]<ref name=pettingill/><ref>{{Cite journal| last1= Hausmann| first1= F.| last2= Arnold| first2=K.E.| last3= Marshall| first3= N.J. | last4= Owens| first4= I.P.F.|year=2003|title=Ultraviolet signals in birds are special|journal=Proceedings of the Royal Society B|volume= 270|pages= 61–67| doi=10.1098/rspb.2002.2200| pmid= 12590772| issue= 1510|pmc=1691211}}</ref><ref>{{Cite journal|title= Carotenoids need structural colours to shine|first1= Matthew D|last1= Shawkey|first2= Geoffrey E|last2= Hill|journal= Biol. Lett.|year= 2005|volume= 1|issue= 2|pages= 121–124|doi= 10.1098/rsbl.2004.0289|url= http://nature.berkeley.edu/%7Emshawkey/9.pdf|pmid= 17148144|pmc= 1626226|archive-url= https://web.archive.org/web/20090326144121/http://nature.berkeley.edu/%7Emshawkey/9.pdf|archive-date= 26 March 2009}}</ref> is involved in the production of blue colors, [[iridescence]], most [[ultraviolet]] reflectance and in the enhancement of pigmentary colors. Structural iridescence has been reported<ref>{{Cite journal |last1= Vinther |first1= Jakob |first2= Derek E. G. |last2= Briggs |first3= Julia |last3= Clarke |first4= Gerald |last4= Mayr |first5= Richard O. |last5= Prum |year= 2009 |pages= 128–31 |issue= 1 |volume= 6 |title= Structural coloration in a fossil feather |journal= [[Biology Letters]] |doi= 10.1098/rsbl.2009.0524 |pmc= 2817243 |pmid= 19710052 |url= http://www.eeb.yale.edu/prum/pdf/Vinther%20et%20al%202010.pdf |access-date= 19 July 2010 |archive-url= https://web.archive.org/web/20100621083621/http://www.eeb.yale.edu/prum/pdf/Vinther%20et%20al%202010.pdf |archive-date= 21 June 2010 }}</ref> in fossil feathers dating back 40 million years. White feathers lack pigment and scatter light diffusely; [[albinism in birds]] is caused by defective pigment production, though structural coloration will not be affected (as can be seen, for example, in blue-and-white [[budgerigar]]s).

[[File:BWfeather.jpg|thumb|upright|A feather with no pigment]]
The blues and bright greens of many [[parrot]]s are produced by constructive interference of light reflecting from different layers of structures in feathers. In the case of green plumage, in addition to yellow,<!-- was: carotinoid, but according to the psittacofulvin source Psittaciformes this might not be correct --> the specific feather structure involved is called by some the Dyck texture.<ref>{{Cite journal|last= Dyck |first=J.|title= Structure and spectral reflectance of green and blue feathers of the Lovebird (''Agapornis roseicollis'')| journal= Biol. SKR.| year= 1971|volume=18|pages=1–67}}</ref><ref>{{Cite journal|journal=The Auk|volume=121|issue=3|pages=652–655|year=2005|title=Feathers at a fine scale|last1=Shawkey|first1=M. D.|first2=G. E.|last2=Hill|doi=10.1642/0004-8038(2004)121[0652:FAAFS]2.0.CO;2|doi-access=free}}</ref> Melanin is often involved in the absorption of light; in combination with a yellow pigment, it produces a dull olive-green.

[[File:Pedro Américo - D. Pedro II na abertura da Assembléia Geral (cropped).jpg|thumb|Emperor [[Pedro II of Brazil]] wearing a wide collar of orange toucan feathers around his shoulders and elements of the [[Imperial Regalia of Brazil|Imperial Regalia]]. Detail from a painting by [[Pedro Américo]]]]
In some birds, feather colors may be created, or altered, by secretions from the [[uropygial gland]], also called the preen gland. The yellow bill colors of many hornbills are produced by such secretions. It has been suggested that there are other color differences that may be visible only in the ultraviolet region,<ref name=delhey>{{Cite journal|last1=Delhey|first1=K|first2=A.|last2=Peters|first3=B.|last3=Kempenaers|year=2007|title=Cosmetic coloration in birds: occurrence, function and evolution|journal=Am. Nat.|volume=169|issue=S1|pages=S145–158|url=http://www.orn.mpg.de/documents/peters/Delhey_AmNat2007_copy.pdf|doi=10.1086/510095|pmid=19426089|bibcode=2007ANat..169S.145D|s2cid=29592388|archive-url=https://web.archive.org/web/20071203190459/http://www.orn.mpg.de/documents/peters/Delhey_AmNat2007_copy.pdf|archive-date=3 December 2007}}</ref> but studies have failed to find evidence.<ref>{{Cite journal|last1= Delhey| first1= K.| first2= A. |last2= Peters| first3= P. H. W.| last3= Biedermann |first4= B. |last4= Kempenaers|year=2008|title=Optical properties of the uropygial gland secretion: no evidence for UV cosmetics in birds|journal=Naturwissenschaften|doi=10.1007/s00114-008-0406-8|volume=95|pages=939–46| pmid= 18560743| issue= 10| bibcode = 2008NW.....95..939D |doi-access= free|hdl= 11858/00-001M-0000-0010-509C-A|hdl-access= free}}</ref> The oil secretion from the uropygial gland may also have an inhibitory effect on feather bacteria.<ref>{{Cite journal|last1=Shawkey|first1=M. D.|first2=S. R.|last2=Pillai|first3=G. E.|last3=Hill|year=2003|title=Chemical warfare? Effects of uropygial oil on feather-degrading bacteria|journal=Journal of Avian Biology|volume=34|pages=345–349|url=http://nature.berkeley.edu/~mshawkey/2.pdf|doi=10.1111/j.0908-8857.2003.03193.x|issue=4|archive-url=https://web.archive.org/web/20080910205855/http://nature.berkeley.edu/~mshawkey/2.pdf|archive-date=10 September 2008}}</ref>

The reds, orange and yellow colors of many feathers are caused by various carotenoids. Carotenoid-based pigments might be honest signals of fitness because they are derived from special diets and hence might be difficult to obtain,<ref>{{cite journal | doi = 10.2307/2408316 | pmid = 28563214 | last1 = Endler | first1 = J. A. | year = 1980 | title = Natural selection on color patterns in Poeci-lia reticulata | jstor = 2408316| journal = Evolution | volume = 34 | issue = 1| pages = 76–91 }}</ref><ref>{{Cite journal|last1= Badyaev |first1=A. V. |last2= Hill |first2= G. E.| year=2000|title=Evolution of sexual dichromatism: contribution of carotenoid versus melanin-based colouration|journal=Biological Journal of the Linnean Society|volume=69|pages=153–172|doi=10.1111/j.1095-8312.2000.tb01196.x|issue=2|s2cid=201965078 |doi-access=free}}</ref> and/or because carotenoids are required for immune function and hence sexual displays come at the expense of health.<ref>{{cite journal | last= Lozano |first= G. A. |s2cid= 86971117 | year = 1994 | title = Carotenoids, parasites, and sexual selection |journal = Oikos | volume = 70 |issue= 2 | pages = 309–311 | doi=10.2307/3545643|jstor= 3545643 |bibcode= 1994Oikos..70..309L }}</ref>

A bird's feathers undergo wear and tear and are replaced periodically during the bird's life through [[molt]]ing. New feathers, known when developing as [[pin feather|blood, or pin feathers]], depending on the stage of growth, are formed through the same follicles from which the old ones were fledged. The presence of melanin in feathers increases their resistance to abrasion.<ref>{{Cite journal|last=Bonser|first=R. H. C.|year=1995|title=Melanin and the abrasion resistance of feathers|jstor=1369048|journal=Condor|url=http://sora.unm.edu/node/105022|volume=97|pages=590–591|doi=10.2307/1369048|issue=2|url-status=live|archive-url=https://web.archive.org/web/20140223002132/https://sora.unm.edu/node/105022|archive-date=23 February 2014}}</ref> One study notes that melanin based feathers were observed to degrade more quickly under bacterial action, even compared to unpigmented feathers from the same species, than those unpigmented or with carotenoid pigments.<ref>{{Cite journal|journal=Ardeola|volume=51|issue=2|year=2004|pages=375–383|title=The evolution of bird plumage colouration: A role for feather-degrading bacteria?|last1=Grande|first1=J. M.|last2=Negro|first2=J. J.|first3=M. J.|last3=Torres|url=http://www.ardeola.org/files/Ardeola_51(2)_375-383.pdf|url-status=live|archive-url=https://web.archive.org/web/20080910205855/http://www.ardeola.org/files/Ardeola_51(2)_375-383.pdf|archive-date=10 September 2008}}</ref> However, another study the same year compared the action of bacteria on pigmentations of two song sparrow species and observed that the darker pigmented feathers were more resistant; the authors cited other research also published in 2004 that stated increased melanin provided greater resistance. They observed that the greater resistance of the darker birds confirmed [[Gloger's rule]].<ref>{{Cite journal|last1=Burtt|first1=Edward H. Jr.|last2=Ichida|first2=Jann M.|year=2004|title=Gloger's Rule, feather-degrading bacteria, and color variation among Song Sparrows|journal=Condor|volume=106|issue=3|pages=681–686|doi=10.1650/7383|s2cid=5857742|url=http://www.public.asu.edu/~kjmcgraw/pubs/Condor04b.pdf|url-status=live|archive-url=https://web.archive.org/web/20121120194024/http://www.public.asu.edu/~kjmcgraw/pubs/Condor04b.pdf|archive-date=20 November 2012}}</ref>

Although sexual selection plays a major role in the development of feathers, in particular, the color of the feathers it is not the only conclusion available. New studies are suggesting that the unique feathers of birds are also a large influence on many important aspects of avian behavior, such as the height at which different species build their nests. Since females are the prime caregivers, evolution has helped select females to display duller colors down so that they may blend into the nesting environment. The position of the nest and whether it has a greater chance of being under predation has exerted constraints on female birds' plumage.<ref name="ReferenceA">{{cite journal | last1 = Martin | first1 = T. E. | last2 = Badyaev | first2 = A. V. | year = 1996 | title = Sexual dichromatic in birds; importance of nest predation and nest location for females versus males | journal = Evolution | volume = 50 | issue = 6| pages = 2454–2460 | doi=10.2307/2410712| jstor = 2410712 | pmid = 28565684 }}</ref> A species of bird that nests on the ground, rather than the canopy of the trees, will need to have much duller colors in order not to attract attention to the nest. The height study found that birds that nest in the canopies of trees often have many more predator attacks due to the brighter color of feathers that the female displays.<ref name="ReferenceA"/> Another influence of evolution that could play a part in why feathers of birds are so colorful and display so many patterns could be due to that birds developed their bright colors from the vegetation and flowers that thrive around them. Birds develop their bright colors from living around certain colors. Most bird species often blend into their environment, due to some degree of camouflage, so if the species habitat is full of colors and patterns, the species would eventually evolve to blend in to avoid being eaten. Birds' feathers show a large range of colors, even exceeding the variety of many plants, leaf, and flower colors.<ref>{{cite journal |last1= Caswell Stoddard| first1= Mary | last2= Prum| first2= Richard O. |year=2011 |title=How colorful are birds? Evolution of the avian plumage color gamut |journal=Behavioral Ecology |volume=22 |issue=5 |pages=1042–1052 |doi=10.1093/beheco/arr088 |doi-access=free |hdl=10.1093/beheco/arr088 |hdl-access=free }}</ref>