Editing Hummingbird (section)

===Feather colors===
[[File:AnnasHummingbirdPaloAltoNorvig.jpg|upright|thumb|Male Anna's hummingbird showing iridescent crown and gorget feathers]]

The hummingbird plumage coloration [[gamut]], particularly for blue, green, and purple colors in the gorget and crown of males, occupies 34% of the total color space for bird feathers.<ref name=venable/> White (unpigmented) feathers have the lowest incidence in the hummingbird color gamut.<ref name=venable/> Hummingbird plumage color diversity evolved from sexual and social selection on plumage coloration, which correlates with the rate of hummingbird species development over millions of years.<ref name=venable/> Bright plumage colors in males are part of aggressive [[competition (biology)|competition]] for flower resources and mating.<ref name=venable/><ref name="learner"/> The bright colors result from [[pigment]]ation in the feathers and from [[Prism (optics)|prismal]] cells within the top layers of feathers of the head, gorget, breast, back and wings.<ref name=venable/><ref name="williamson">{{Cite book |last=Williamson S |url=https://books.google.com/books?id=XtZ1xotyal8C&q=Iridescent+colors+hummingbird+feathers.&pg=PA28 |title=A Field Guide to Hummingbirds of North America. Section: Plumage and Molt |publisher=Houghton Mifflin Harcourt |year=2001 |isbn=978-0-618-02496-4 |pages=13–18}}</ref> When [[sunlight]] hits these cells, it is split into wavelengths that reflect to the observer in varying degrees of intensity,<ref name="williamson"/> with the feather structure acting as a [[diffraction grating]].<ref name="williamson"/> Iridescent hummingbird colors result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of [[melanin]], a pigment,<ref name=venable/><ref name="learner">{{Cite web |date=2015 |title=Hummingbird characteristics |url=http://www.learner.org/jnorth/search/HummerNotes1.html |url-status=dead |archive-url=https://web.archive.org/web/20161111085045/http://learner.org/jnorth/search/HummerNotes1.html |archive-date=2016-11-11 |access-date=2010-08-30 |website=learner.org |publisher=Annenberg Learner, The Annenberg Foundation}}</ref> and may also be colored by [[carotenoid]] pigmentation and more subdued black, brown or gray colors dependent on melanin.<ref name="williamson"/>

By merely shifting position, feather regions of a muted-looking bird can instantly become fiery red or vivid green.<ref name="williamson"/> In courtship displays for one example, males of the colorful Anna's hummingbird orient their bodies and feathers toward the sun to enhance the display value of iridescent plumage toward a female of interest.<ref>{{Cite journal |last=Hamilton|first= W.J. |year=1965 |title=Sun-oriented display of the Anna's hummingbird |url=https://sora.unm.edu/sites/default/files/journals/wilson/v077n01/p0038-p0044.pdf |journal=The Wilson Bulletin |volume=77 |issue=1}}</ref>

One study of Anna's hummingbirds found that dietary [[protein]] was an influential factor in feather color, as birds receiving more protein grew significantly more colorful [[crown (anatomy)|crown]] feathers than those fed a low-protein diet.<ref name="jeb">{{Cite journal |author1=Meadows, M.G. |author2=Roudybush, T.E. |author3=McGraw, K.J. |year=2012 |title=Dietary protein level affects iridescent coloration in Anna's hummingbirds, ''Calypte anna'' |journal=Journal of Experimental Biology |volume=215 |issue=16 |pages=2742–750 |doi=10.1242/jeb.069351 |pmc=3404802 |pmid=22837446|bibcode=2012JExpB.215.2742M }}</ref> Additionally, birds on a high-protein diet grew yellower (higher [[hue]]) green tail feathers than birds on a low-protein diet.<ref name="jeb"/>