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Article: Feather
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[[File:Types de plumes. - Larousse pour tous, -1907-1910-.jpg|thumb|Feather variations]]
'''Feathers''' are one of the [[epidermis (zoology)|epidermal]] growths that form the distinctive outer covering, or [[plumage]], on [[bird]]s and some non-avian theropod dinosaurs. They are considered the most complex [[integumentary]] structures found in vertebrates,<ref name=Prum2002>{{Cite journal|author=[[Richard Prum|Prum, Richard O]]. & AH Brush|year=2002|title=The evolutionary origin and diversification of feathers|journal=[[The Quarterly Review of Biology]]|volume=77|issue=3 |url= |pages=261–295|doi=10.1086/341993|pmid=12365352 |accessdate=7 July 2010}}</ref><ref name="Prum2003">{{Cite journal|doi=10.1038/scientificamerican0303-84 |date = March 2003|author=Prum, R.O., & Brush, A.H |title=Which Came First, the Feather or the Bird? |journal=[[Scientific American]] |volume=288 |issue=3 |pages=84–93 |url= |accessdate=7 July 2010 |postscript=<!--None--> |pmid=12616863}}</ref> and indeed a premier example of a complex evolutionary novelty.<ref name=Prum1999>{{Cite journal|doi=10.1002/(SICI)1097-010X(19991215)285:4<291::AID-JEZ1>3.0.CO;2-9|year=1999 |author=Prum, Richard O |title=Development and Evolutionary Origin of Feathers |journal=Journal of Experimental Zoology (Molecular and Developmental Evolution) |volume=285|issue=4 |pages=291–306 |pmid=10578107 |url= |accessdate=7 July 2010|postscript=<!--None-->}}</ref> They are among the characteristics that distinguish the extant [[Aves]] from other living groups. Feathers have also been noticed in those [[Theropoda]] which have been termed [[feathered dinosaurs]]. Although feathers cover most parts of the body of birds, they arise only from certain well-defined tracts on the skin. They aid in flight, thermal insulation, waterproofing and coloration that helps in communication and [[crypsis|protection]].<ref name=pettingill>{{Cite book|author=Pettingill, OS Jr.|year=1970|title=Ornithology in Laboratory and Field. Fourth edition|publisher=Burgess Publishing Company|isbn=808716093|pages=29–58}}</ref>
==Structure and characteristics==
[[File:Parts of feather modified.jpg|thumb|'''Parts of a feather:'''<br/>1. Vane<br/>2. Rachis<br/>3. Barb<br/>4. Afterfeather<br/>5. Hollow shaft, calamus]]
[[File:Parrot-feather.jpg|thumb|Feather structure of a [[Blue-and-yellow Macaw]]]][[File:FeatherMagnified.JPG|thumb|[[Budgerigar]] feather, magnified, showing interlocking barbules]]
Feathers are among the most complex [[Integumentary system|integument]]ary [[appendages]] found in [[Vertebrata|vertebrates]] and are formed in tiny follicles in the [[Epidermis (zoology)|epidermis]], or outer skin layer, that produce [[keratin]] [[protein]]s. The [[β-keratin]]s in feathers, [[beak]]s and claws — and the [[claw]]s, [[scale (zoology)|scale]]s and [[Animal shell|shell]]s of [[reptile]]s — are composed of protein strands [[hydrogen bond|hydrogen-bonded]] into [[beta sheet|β-pleated sheets]], which are then further twisted and [[cross-link|crosslinked]] by [[disulfide]] bridges into structures even tougher than the [[α-keratin]]s of mammalian [[hair]], [[horn (anatomy)|horns]] and [[hoof]].<ref>{{Cite journal|journal=Biophys J.|year=1961|volume=1|issue=6|pages=489–515|title=Studies on the Structure of Feather Keratin: II. A β-Helix Model for the Structure of Feather Keratin|author=R. Schor and S. Krimm |doi=10.1016/S0006-3495(61)86904-X |pmid=19431311 |pmc=1366335 |bibcode=1961BpJ.....1..489S}}</ref><ref>{{Cite journal|title=The Structure of Feather Rachis Keratin|author=Linus Pauling and Robert B. Corey|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=37|issue=5|year=1951|pages=256–261|doi=10.1073/pnas.37.5.256|pmid=14834148|pmc=1063351|bibcode = 1951PNAS...37..256P }}</ref> The exact signals that induce the growth of feathers on the skin are not known but it has been found that the transcription factor cDermo-1 induces the growth of feathers on skin and scales on the leg.<ref>{{Cite journal|author=Hornik, C., Krishan, K., Yusuf, F., Scaal, M., & Brand-Saberi, B.|year=2005|title=cDermo-1 misexpression induces dense dermis, feathers, and scales|journal=Developmental Biology|volume=277|issue=1|pages=42–50|doi=10.1016/j.ydbio.2004.08.050|pmid=15572138}}</ref>
[[File:FeatherLocking.png|thumb|left|Feather microstructure showing interlocking barbules.]]
{{See also|Flight feather|Down feather}}
There are two basic types of feather: '''vaned feathers''' which cover the exterior of the body, and '''[[down feather]]s''' which are underneath the vaned feathers. The [[pennaceous feather]]s are vaned feathers. Also called '''contour feathers''', pennaceous feathers arise from tracts and cover the whole body. A third rarer type of feathers, '''filoplumes''', is hairlike and (if present in a bird) grows along the fluffy down feathers. In some passerines, filoplumes arise exposed beyond the contour feathers on the neck.<ref name=Prum2002/> The remiges, or [[flight feather]]s of the wing, and rectrices, the flight feathers of the tail are the most important feathers for flight. A typical vaned feather features a main shaft, called the [[rachis]]. Fused to the rachis are a series of branches, or '''barbs'''; the barbs themselves are also branched and form the '''barbules'''. These barbules have minute hooks called '''barbicels''' for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap much air and provide excellent thermal insulation. At the base of the feather, the rachis expands to form the hollow tubular ''calamus'' (or [[quill]]) which inserts into a [[Hair follicle|follicle]] in the [[skin]]. The basal part of the calamus is without vanes. This part is embedded within the skin follicle and has an opening at the base (proximal umbilicus) and a small opening on the side (distal umbilicus).<ref name=atlas>{{Cite book|title=A color atlas of avian anatomy|author=McLelland, J.|publisher=W.B. Saunders Co.|year=1991|isbn=0721635369}}</ref>
Hatchling birds of some species have a special kind of natal down (neossoptiles) and these are pushed out when the normal feathers (teleoptiles) emerge.<ref name=Prum2002 />
Flight feathers are stiffened so as to work against the air in the downstroke but yield in other directions. It is noted that the pattern of orientation of β-keratin fibers in the feathers of flying birds differs from that in flightless birds. The fibers are better aligned in the middle of the feather and less aligned towards the tips.<ref>{{Cite journal|author=Cameron, G., Wess, T., & Bonser, R.|year=2003|title=Young's modulus varies with differential orientation of keratin in feathers|journal=Journal of Structural Biology|volume=143|issue=2|pages=118–23|doi=10.1016/S1047-8477(03)00142-4|pmid=12972348}}</ref><ref>{{Cite journal|author=Bonser, R., Saker, L., & Jeronimidis, G.|year=2004|title=Toughness anisotropy in feather keratin|journal=Journal of Materials Science|volume=39|issue=8|pages=2895–2896|doi=10.1023/B:JMSC.0000021474.75864.ff|bibcode = 2004JMatS..39.2895B }}</ref>
Feathers insulate birds from water and cold temperatures. They may also be plucked to line the nest and provide insulation to the eggs and young. The individual feathers in the wings and tail play important roles in controlling flight. Some species have a [[Crest (feathers)|crest]] of feathers on their heads. Although feathers are light, a bird's plumage weighs two or three times more than its skeleton, since many bones are hollow and contain air sacs. Color patterns serve as [[camouflage]] against [[predator]]s for birds in their habitats, and by predators looking for a meal. As with fish, the top and bottom colors may be different to provide camouflage during flight. Striking differences in feather patterns and colors are part of the [[sexual dimorphism]] of many bird species and are particularly important in selection of mating pairs. In some cases there are differences in the UV reflectivity of feathers across sexes even though no differences in color are noted in the visible range.<ref>{{Cite journal|title=The ubiquity of avian ultraviolet plumage reflectance|author=Muir D. Eaton and Scott M. Lanyon|journal=Proceedings: Biological Sciences|volume=270|issue=1525|year=2003|pages=1721–1726|doi=10.1098/rspb.2003.2431|pmid=12965000|pmc=1691429}}</ref> The wing feathers of male [[Club-winged Manakin]]s ''Machaeropterus deliciosus'' have special structures that are used to produce sounds by [[stridulation]].<ref>{{Cite journal|title=Courting Bird Sings with Stridulating Wing Feathers|author=Bostwick, Kimberly S. and Richard O. Prum|year=2005|journal=Science|volume=309|issue=5735|pages=736|doi=10.1126/science.1111701|pmid=16051789 |url= |accessdate=19 July 2010 }}</ref>
[[File:GuineaFeather.jpg|thumb|left|A contour feather from a [[Guinea fowl]]]]
Some birds have a supply of [[powder down]] feathers which grow continuously, with small particles regularly breaking off from the ends of the barbules. These particles produce a [[Powder (substance)|powder]] that sifts through the feathers on the bird's body and acts as a waterproofing agent and a feather [[conditioner (chemistry)|conditioner]]. Powder down has evolved independently in several taxa and can be found in down as well as pennaceous feathers. They may be scattered in plumage in the pigeons and parrots or in localized patches on the breast, belly or flanks as in herons and frogmouths. Herons use their bill to break the feathers and to spread them while cockatoos may use their head as a powder puff to apply the powder.<ref name=delhey/> Waterproofing can be lost by exposure to [[emulsion|emulsifying agents]] due to human [[pollution]]. Feathers can become waterlogged and birds may sink. It is also very difficult to clean and rescue birds whose feathers have been fouled by [[oil spill]]s. The feathers of cormorants soak up water and help in reducing buoyancy and thereby allowing the birds to swim submerged.<ref>{{Cite journal|author=Ribak, G., Weihs, D. and Arad, Z.|year=2005|title=Water retention in the plumage of diving great cormorants ''Phalacrocorax carbo sinensis''|journal=J. Avian Biol.|volume=36|pages=89–95|doi=10.1111/j.0908-8857.2005.03499.x|issue=2}}</ref>
[[File:BarbetRictalBristle.jpg|thumb|Rictal bristles of a [[White-cheeked Barbet]]]]
[[Bristle]]s are stiff, tapering feathers with a large rachis but few barbs. '''Rictal bristles''' are bristles found around the eyes and bill. They may serve a similar purpose to [[eyelash]]es and [[vibrissae]] in [[mammal]]s. It has been suggested that they may aid insectivorous birds in prey capture or that it may have sensory functions, however there is no clear evidence.<ref>{{Cite web|url= |title=The role of avian rictal bristles |author=Roger J. Lederer |year=1972 |work=Wilson. Bull. 84, 193-97 [pdf] |publisher=[[University of New Mexico]] |accessdate=16 September 2010}}</ref> In one study, Willow Flycatchers (''Empidonax traillii'') were found to catch insects equally well before and after removal of the rictal bristles.<ref>Conover, M. R., and D. E. Miller (1980) Rictal bristle function in willow flycatcher. Condor 82:469-471.</ref>
[[Grebe]]s are peculiar in their habit of ingesting their own feathers and also feeding them to their young. Observations on the diet and feather eating frequency suggest that ingesting feathers particularly down from their flanks aids in forming easily ejectable pellets along with their diet of fish.<ref>{{Cite journal|title=Feather eating in Great Crested Grebes ''Podiceps cristatus'': a unique solution to the problems of debris and gastric parasites in fish-eating birds|author=Piersma, T & M R van Eerden|journal=Ibis|volume=131|issue=4|pages=477–486|year=1989|doi=10.1111/j.1474-919X.1989.tb04784.x}}</ref>
[[File:Pterylae.svg|thumb|Feather tracts or pterylae and their naming]]
Contour feathers are not uniformly distributed on the skin of the bird except in some groups such as the [[Penguin]]s, ratites and screamers.<ref>{{Cite journal|title=A Study of the Pterylosis and Pneumaticity of the Screamer|jstor=1364475|author=Demay, Ida S.|journal=The Condor|volume=42|issue=2|year=1940|pages=112–118|doi=10.2307/1364475}}</ref> In most birds the feathers grow from specific tracts of skin called pterylae while there are regions which are free of feathers called apterylae. Filoplumes and down may arise from the apteriae, regions between the pterylae. The arrangement of these feather tracts, pterylosis or pterylography, varies across bird families and has been used in the past as a means for determining the evolutionary relationships of bird families.<ref>{{Cite journal|journal=Journal of Ornithology|title=Do nine-primaried passerines have nine or ten primary feathers? The evolution of a concept|volume=146|issue=2|pages=121–126|year=2005|author=K. Susanna S. Hall|doi=10.1007/s10336-004-0070-5}}</ref><ref>{{Cite journal|author=Pycraft, W. P.|year=1895|title=On the pterylography of the hoatzin (''Opisthocomus cristatus'')|journal=Ibis|volume=37|pages=345–373|doi=10.1111/j.1474-919X.1895.tb06744.x|issue=3}}</ref>
[[File:Red feather pigments.jpg|thumb|left|250px|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 the presence of pigments, or by microscopic [[refraction|refractive]] structures, 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]] &ndash; 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|author=McGraw KH & MC Nogare|doi=10.1098/rsbl.2004.0269|pmid=17148123|pmc=1629064}}</ref> (found in some parrots) and the red [[turacin]] and green [[turacoverdin]] ([[porphyrin]] pigments found only in [[turaco]]s). Structural coloration<ref name=pettingill/><ref>{{Cite journal|author=Hausmann, F., Arnold, K.E., Marshall, N.J. & Owens, I.P.F.|year=2003|title=Ultraviolet signals in birds are special|journal=Proc. R. Soc. 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|author=Matthew D Shawkey and Geoffrey E Hill|journal= Biol Lett.|year=2005 |volume =1|issue= 2 |pages=121–124|doi=10.1098/rsbl.2004.0289|url=|format=PDF|pmid= 17148144|pmc= 1626226}}</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|last=Vinther|first=Jakob |coauthors=Derek E. G. Briggs; Julia Clarke; Gerald Mayr; Richard O. 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= |accessdate=19 July 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 e.g. in blue-and-white [[budgerigar]]s).
[[File:BWfeather.jpg|thumb|130px|A feather with no pigment]]
For example, the blues and bright greens of many [[parrot]]s are produced by constructive interference of light reflecting from different layers of the structures in feathers, in the case of green plumage in addition to the yellow<!-- was: carotinoid, but according to the psittacofulvin source Psittaciformes this might not be correct --> pigments; the specific feather structure involved is sometimes called the Dyck texture.<ref>{{Cite journal|author=Dyck 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|author=Shawkey MD & G E Hill|url=|format=PDF|doi=10.1642/0004-8038(2004)121[0652:FAAFS]2.0.CO;2}}</ref> Melanin is often involved in the absorption of some of the light; in combination with yellow pigment it produces dull olive-greens.
In some birds, the feather colors may be created or altered by uropygial gland secretions. The yellow bill colors of many hornbills are produced by preen gland secretions. Other differences that may only be visible in the ultraviolet region have been suggested<ref name=delhey>{{Cite journal|author=Delhey K, A. Peters, and B. Kempenaers|year=2007|title=Cosmetic coloration in birds: occurrence, function and evolution|journal=Am. Nat.|volume=169|pages=S145–158|url=|format=PDF|doi=10.1086/510095|pmid=19426089}}</ref> but studies have failed to find evidence.<ref>{{Cite journal|author=Delhey, K., A. Peters, PHW Biedermann & B 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 }}</ref> Uropygial oil secretion may also have an inhibitory effect on feather bacteria.<ref>{{Cite journal|author=Shawkey, M.D., S.R. Pillai, and G.E. 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=|format=PDF|doi=10.1111/j.0908-8857.2003.03193.x|issue=4}}</ref>
A bird's feathers undergo wear and tear and are replaced periodically during its life through [[molt]]ing. New feathers, known as [[pin feather|blood, or pin feathers]] (depending on the stage of growth) when developing, are formed through the same follicle from which the old ones were fledged. The presence of melanin in feathers increases their resistance to abrasion.<ref>{{Cite journal|author=Bonser, R. H. C.|year=1995|title=Melanin and the abrasion resistance of feathers|jstor=1369048|journal=Condor|volume=97|pages=590–591|doi=10.2307/1369048|issue=2}}</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?|author=Grande JM, Negro JJ & MJ Torres|url=|format=PDF}}</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 and they 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|author=Burtt, Edward H. Jr. & Ichida, 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|url=|format=PDF}}</ref> The evolution of coloration is based on sexual selection and it has been suggested that carotenoid-based pigments may have evolved since they are likely to be more honest signals of fitness because they are derived from special diets,<ref>{{cite journal | doi = 10.2307/2408316 | 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|author=Badyaev AV & Hill GE|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}}</ref> or because carotenoids are also required for immune function.<ref>Lozano, G. A. 1994. Carotenoids, parasites, and sexual selection. Oikos 70: 309-311</ref>
The feather surface is the home for some ectoparasites, notably feather lice ([[Phthiraptera]]) and feather mites. Feather lice typically live on a single host and can move only from parents to chicks or mating birds and occasionally by [[phoresy]]. This life history has resulted in most of the species being specific to the host and coevolving with the host, making them of interest in phylogenetic studies.<ref>{{Cite journal|author=Toon, A., & Hughes, J.|year=2008|title=Are lice good proxies for host history? A comparative analysis of the Australian magpie, ''Gymnorhina tibicen'', and two species of feather louse|journal=Heredity|volume=101|issue=2|pages=127–135|doi=10.1038/hdy.2008.37|pmid=18461081}}</ref>
[[Feather holes]] are chewing traces of lice (most probably ''[[Brueelia]]'' spp. lice) on the wing and tail feathers. They were described on [[barn swallow]]s, and because of easy countability, many evolutionary, ecological, and behavioral publications use them to quantify the intensity of infestation.
Interestingly, parasitic cuckoos which grow up in the nests of other species also have host specific feather lice and these seem to be transmitted only after they leave the host nest.<ref>{{Cite journal|author=Brooke, M. de L. and Hiroshi Nakamura|year=1998|title=The acquisition of host-specific feather lice by common cuckoos (''Cuculus canorus'')|journal=Journal of Zoology|volume=244|pages=167–173|doi=10.1017/S0952836998002027|issue=2}}</ref>
Birds maintain their feather condition by bathing in water, dust bathing and preening. A peculiar behavior of birds, [[anting (bird activity)|anting]], where ants are introduced into the plumage was suggested to help in reducing parasites but no supporting evidence has been found.<ref>{{Cite journal|author=Revis, Hannah C., and Deborah A. Waller|year=2004|title=Bactericidal and fungicidal activity of ant chemicals on feather parasites: an evaluation of anting behavior as a method of self-medication in songbirds| journal=Auk|volume=121|issue=4|pages=1262–1268|doi=10.1642/0004-8038(2004)121[1262:BAFAOA]2.0.CO;2}}</ref>
==Human usage==
[[File:Shaft of Indian Peacock tail feather.jpg|thumb|right|Part of Indian Peacock tail feather]]
Feathers have a number of utilitarian, cultural and religious uses.
===Utilitarian functions===
Feathers are both soft and excellent at trapping [[heat]]; thus, they are sometimes used in high-class [[bedding]], especially [[pillow]]s, [[blanket]]s, and [[mattress]]es. They are also used as filling for winter [[clothing]], such as quilted [[Coat (clothing)|coat]]s and [[sleeping bag]]s; [[goose]] and [[eider]] down have great ''loft'', the ability to expand from a compressed, stored state to trap large amounts of compartmentalized, insulating air.<ref>{{Cite journal|journal=Journal of Materials Science Letter|title=The structural mechanical properties of down feathers and biomimicking natural insulation materials|volume=18|issue=21|pages=1769–1770|year=1999|author=Bonser, R.H.C. & Dawson, C.|doi=10.1023/A:1006631328233}}</ref>
Bird feathers have long been used for [[fletching]] [[arrow (weapon)|arrow]]s. Colorful feathers such as those belonging to [[pheasant]]s have been used to decorate [[fishing lure]]s.
Feathers of large birds (most often [[Goose|geese]]) have been and are used to make [[quill]] pens. The word '''pen''' itself is derived from the Latin ''penna'' for feather.<ref>{{cite web|url=|title=<sup>3</sup>Pen|work=The Merriam-Webster Online Dictionary|publisher=Merriam-Webster, Inc|accessdate=16 October 2010}}</ref> In French, ''plume'' can mean either ''feather'' or ''pen''.
Feathers are also valuable in aiding the identification of species in forensic studies, particularly in bird strikes to aircraft. The ratios of hydrogen isotopes in feathers help in determining the geographic origins of birds.<ref>{{Cite journal|journal=Oecologia|title=Global application of stable hydrogen and oxygen isotopes to wildlife forensics|volume=143|issue=3|pages=337–348|doi=10.1007/s00442-004-1813-y|year=2005|pmid=15726429|author1=Bowen, Gabriel J|author2=Wassenaar, Leonard I|author3=Hobson, Keith A}}</ref> Feathers may also be useful in the non-destructive sampling of pollutants.<ref>{{Cite journal|author=Jaspers, V., Voorspoels, S., Covaci, A., Lepoint, G., & Eens, M.|year=2007|title=Evaluation of the usefulness of bird feathers as a non-destructive biomonitoring tool for organic pollutants: A comparative and meta-analytical approach|journal=Environment International|volume=33|issue=3|pages=328–337|doi=10.1016/j.envint.2006.11.011|pmid=17198730}}</ref>
The poultry industry produces a large amount of feathers as waste, and like other forms of keratin, these are slow in their decomposition. Feather waste has been used in a number of industrial applications as a medium for culturing microbes,<ref>{{Cite journal|title=Use of feather-based culture media for the production of mosquitocidal bacteria|doi=10.1016/j.biocontrol.2007.04.019|journal=Biological Control|volume=43|issue=1|pages=49–55|author=Subbiah Poopathi, S. Abidha|year=2007}}</ref> biodegradeable polymers,<ref>{{Cite journal|author=Schmidt, W.F., Barone, J.R.|year=2004|title=New uses for chicken feathers keratin fiber. Poultry Waste Management Symposium Proceedings|pages=99–101}}</ref> and production of enzymes.<ref>{{Cite journal|journal=Food and Bioprocess Technology|title=Use of Poultry Byproduct for Production of Keratinolytic Enzymes|volume=1|issue=3|pages=301–305|year=2008|doi=10.1007/s11947-008-0091-9|author1=Casarin, Franciani|author2=Brandelli, Florencia Cladera-Olivera Adriano|last3=Brandelli|first3=Adriano}}</ref> Feather proteins have been tried as an adhesive for wood board.<ref>{{Cite journal|author=Jiang, Z., Qin, D., Hse, C., Kuo, M., Luo, Z., Wang, G., et al.|year=2008|title=Preliminary Study on Chicken Feather Protein-Based Wood Adhesives|journal=Journal of Wood Chemistry & Technology|volume=28|issue=3|pages=240–246|doi=10.1080/02773810802347073}}</ref>
===In religion and culture===
[[Eagle]] feathers have great [[cultural]] and [[Spirituality|spiritual]] value to [[Native Americans in the United States|American Indians]] in the [[USA]] and [[First Nations]] peoples in [[Canada]] as religious objects. In the United States the [[religious]] use of [[eagle]] and [[hawk]] feathers are governed by the [[eagle feather law]], a federal law limiting the possession of eagle feathers to certified and enrolled members of federally recognized Native American tribes.
Various birds and their plumages serve as cultural icons throughout the world, from the hawk in ancient Egypt to the bald eagle and the [[turkey (bird)]] in the United States. In [[Greek mythology]], Daedelus the inventor and [[Icarus (mythology)|Icarus]] tried to escape his prison by attaching feathered wings to his shoulders with wax, which was melted by the Sun.
In South America, brews made from the feathers of Condors are used in traditional medications.<ref>{{Cite journal|author=Steve Froemming|title=Traditional use of the Andean flicker (Colaptes rupicola) as a galactagogue in the Peruvian Andes|journal=Journal of Ethnobiology and Ethnomedicine| year=2006|volume=2|pages=23 |doi=10.1186/1746-4269-2-23|pmid=16677398|pmc=1484469}}</ref> In India, feathers of the [[Indian Peacock]] have been used in traditional medicine for snakebite, infertility and coughs.<ref>{{Cite journal|author=Murari, S.K., Frey, F.J., Frey, B.M., Gowda, T.V., Vishwanath, B.S.|year=2005|title=Use of ''Pavo cristatus'' feather extract for the better management of snakebites: Neutralization of inflammatory reactions|journal=Journal of Ethnopharmacology|volume=99|issue=2|pages=229–237|doi=10.1016/j.jep.2005.02.027|pmid=15894132}}</ref><ref>{{Cite journal|title=Traditional knowledge on zootherapeutic uses by the Saharia tribe of Rajasthan, India|author=Mahawar, MM & DP Jaroli|journal=J Ethnobiol Ethnomedicine|year=2007|volume=3|pages=25|doi=10.1186/1746-4269-3-25|pmid=17547781|pmc=1892771}}</ref>
During the 18th, 19th, and even 20th Centuries a booming international trade in plumes, to satisfy market demand in North America and Europe for extravagant [[headgear|head-dresses]] as adornment for fashionable women, caused so much destruction (for example, to [[egret]] breeding colonies) that a major campaign against it by conservationists led to the [[Lacey Act]] and caused the fashion to change and the market to finally collapse. [[Frank Chapman]] noted in 1886 that as many as 40 species of birds were used in about three-fourths of the 700 ladies' hats that he observed in New York City.<ref>Doughty, Robin W. 197. Feather Fashions and Bird Preservation, A Study in Nature Protection. University of California Press.</ref><ref>Ehrlich, Paul R.; Dobkin. David S.; Wheye. Darryl (1988) [ Plume Trade] Stanford University</ref><ref>[ Feather trade] Smithsonian Institution</ref>
More recently, rooster plumage has become a popular trend as a hairstyle accessory, with feathers formerly used solely as fishing lures being now used to provide color and style to hair.<ref></ref>
{{Main|Origin of avian flight}}
[[File:Archaeopteryx (Feather).jpg|thumb|right|upright|Fossil feather of [[Archaeopteryx]] ]]
The functional view on the evolution of feathers has traditionally focused on insulation, flight and display. Discoveries of non-flying Late Cretaceous feathered dinosaurs in China however suggest that flight could not have been the original primary function.<ref name=sumida>{{Cite journal|author=Sumida, SS & CA Brochu|year=2000|title=Phylogenetic context for the origin of feathers|doi=10.1093/icb/40.4.486|journal=American Zoologist|volume=40|issue=4|pages=486–503|url=}}</ref> There have been suggestions that feathers may have had their original function in thermoregulation, waterproofing or even as sinks for metabolic wastes such as sulphur.<ref>{{cite journal| title= Explanatory History of the Origin of Feathers|author=Bock, WJ|year=2000| journal= Amer. Zool.|volume=40 |issue=4|pages=478–485 |doi=10.1093/icb/40.4.478}}</ref> While feathers have been suggested as having evolved from reptilian [[scale (zoology)|scales]], there are numerous objections, and more recent explanations have arisen from the paradigm of [[evolutionary developmental biology]].<ref name=Prum2003/> Theories of the scale-based origins of feathers suggest that the planar scale structure was modified for their development into feathers by splitting to form the webbing; however, the developmental process involves a tubular structure arising from a follicle and the tube splitting longitudinally to form the webbing.<ref name=Prum2002/><ref name=Prum2003/> The number of feathers per unit area of skin is higher in smaller birds than in larger birds, and this trend indicates their important role in thermal insulation, since smaller birds lose more heat due to the relatively larger surface area in proportion to their body weight.<ref name=pettingill/> The miniaturization of birds also played a role in the evolution of powered flight.<ref>{{Cite journal|author=De Ricqles, A. J., K. Padian, J. R. Horner, E. T. Lamm, and N. Myhrvold|year=2003|title=Osteohistology of confuciusornis sanctus (theropoda: Aves)|journal=Journal of Vertebrate Paleontology|volume=23|pages=753–761}}</ref> The coloration of feathers is believed to be primarily evolved in response to [[sexual selection]]. In many cases the physiological condition of the birds (especially males) is indicated by the quality of their feathers and this is used (by the females) in [[mate choice]].<ref>{{Cite journal|author=Saino, Nicola, and Riccardo Stradi|year=1999|title=Carotenoid Plasma Concentration, Immune Profile, and Plumage Ornamentation of Male Barn Swallows|journal=American Naturalist|volume=154|issue=4|pages=441–448|doi=10.1086/303246|pmid=10523490}}</ref><ref>{{Cite journal|author=Endler, John A., David A. Westcott, Joah R. Madden, Tim Robson, and Patrick Phillips|year=2005|title=Animal visual systems and the evolution of color patterns: Sensory processing illumiates signal evolution|journal=Evolution|volume=59|issue=8|pages=1795–1818|pmid=16329248}}</ref>
===Feathered dinosaurs===
{{Main|Feathered dinosaurs}}
[[File:Archaeopteryx lithographica (Berlin specimen).jpg|thumb|right|upright|[[Archaeopteryx lithographica]] (Berlin specimen)]]
Several non-avian [[feathered dinosaurs|dinosaurs]] had feathers on their limbs that would not have functioned for flight.<ref name=Prum2003/> One theory is that feathers originally evolved on dinosaurs as a result of [[Thermal insulation|insulation]] properties; those small dinosaurs that then grew longer feathers may have found them helpful in gliding, leading to the evolution of proto-birds like ''[[Archaeopteryx]]'' and ''[[Microraptor]] zhaoianus''. Dinosaurs that had feathers or protofeathers include ''[[Pedopenna]] daohugouensis'',
<ref>{{Cite journal|journal= Naturwissenschaften|title=A new maniraptoran dinosaur from China with long feathers on the metatarsus|volume=92|issue=4|pages=173–177|author=Xu, Xing & Fucheng Zhang|doi=10.1007/s00114-004-0604-y|year= 2005|pmid= 15685441|bibcode=2005NW.....92..173X}}</ref> and ''[[Dilong paradoxus]]'', a [[tyrannosauroid]] which is 60 to 70 million years older than ''[[Tyrannosaurus|Tyrannosaurus rex]]''.<ref>{{Cite journal|author=Xu, Xing|title=Feathered dinosaurs from China and the evolution of major avian characters|journal=Integrative Zoology|volume=1|issue=1|pages=4–11|year=2006|doi=10.1111/j.1749-4877.2006.00004.x|pmid=21395983}}</ref>
The majority of dinosaurs known to have had feathers or protofeathers are [[saurischian]]s, however featherlike "filamentous integumentary structures" are also known from the [[ornithischian]]s ''[[Tianyulong]]'' and ''[[Psittacosaurus]]''.<ref>{{Cite journal|author=Zheng,X. T.,H. L. You,X. Xu and Z. M. Dong|journal=Nature|title=An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures|volume=458|year=2009|pages=333–336|doi=10.1038/nature07856|pmid=19295609|issue=7236}}</ref> The exact nature of these structures is still under study. However, it is believed that the stage 1 feathers such as those seen in these two ornithischians likely functioned in display.<ref name="xu&guo2009"/>
Since the 1990s, dozens of feathered dinosaurs have been discovered in the clade [[Maniraptora]], which includes the clade Avialae and the recent common ancestors of birds, [[Oviraptorosauria]] and [[Deinonychosauria]]. In 1998, the discovery of a feathered oviraptorosaurian, ''Caudipteryx zoui'', challenged the notion that feathers were an exclusive structure of Avialae.<ref>{{Cite journal|doi=10.1038/31635 |author=Ji, Q., P. J. Currie, M. A. Norell, and S. A. Ji |title=Two feathered dinosaurs from northeastern China |journal=Nature |volume=393 |year=1998 |pages=753–761 |issue=6687|bibcode = 1998Natur.393..753Q }}</ref> Buried in the Yixian Formation in Liaoning, China, ''C. zoui'' lived during the Early Cretaceous Period. Present on the forelimbs and tails, their integumentary structure has been accepted as pennaceous vaned feathers based on the rachis and herringbone pattern of the barbs. In the clade Deinonychosauria, the continued divergence of feathers is also apparent in the families [[Troodontidae]] and [[Dromaeosauridae]]. Branched feathers with ranchis, barbs, and barbules were discovered in many members including ''Sinornithosaurus millenii'', a dromaeosaurid found in the Yixian formation (124.6 MYA).<ref>{{Cite journal|doi=10.1038/35065589 |author=Xu, X., H. H. Zhou, and R. O. Prum |title=Branched integumental structures in Sinornithosaurus and the origin of feathers |journal=Nature |volume=410 |issue=6825 |year=2001 |pages=200–204 |pmid=11242078 }}</ref>
Previously, a temporal paradox existed in the evolution of feathers - theropods with highly derived bird-like characteristics occurred at a later time than ''[[Archaeopteryx]]'', suggesting that the descendants of birds arose before the ancestor. However, this paradox was resolved in 2009 with the discovery of ''Anchiornis huxleyi'', found in the Late Jurassic Tiaojishan Formation (160 MYA) in western Liaoning.<ref>{{Cite journal|author=Hu, D. Y., L. H. Hou, L. J. Zhang, and X. Xu |title=A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus |journal=Nature |volume=461 |issue=7264 |year=2009 |pages=640–643 |pmid=19794491 |doi=10.1038/nature08322 |bibcode=2009Natur.461..640H}}</ref><ref>{{Cite journal|author=Xu, X., Q. Zhao, M. Norell, C. Sullivan, D. Hone, G. Erickson, X. L. Wang et al. |title=A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin |journal=Chinese Science Bulletin |volume=54 |year=2009 |pages=430–435 |doi=10.1007/s11434-009-0009-6|issue=3}}</ref> By predating ''Archaeopteryx'', ''Anchornis'' proves the existence of a modernly feathered theropod ancestor, providing insight into the dinosaur-bird transition. The specimen shows distribution of large pennaceous feathers on the forelimbs and tail, implying that pennaceous feathers spread to the rest of the body at an earlier stage in theropod evolution.<ref>{{Cite journal|author=Witmer, L. M. |title=Feathered dinosaurs in a tangle |journal=Nature |volume=461 |issue=7264 |year=2009 |pages=601–602 |pmid=19794481 |doi=10.1038/461601a|bibcode = 2009Natur.461..601W }}</ref> The discovery, in 2011, of feathers preserved in amber, within samples dating to 80 mya, suggests the coexistence of theropods and birds, with both theropod and avian feather types commingled in the samples.<ref></ref>
===Evolutionary stages===
[[File:Feather stages diagram.svg|thumb|right|Diagram illustrating stages of evolution]]
Several studies of feather development in the embryos of modern birds, coupled with the distribution of feather types among various prehistoric bird precursors, have allowed scientists to attempt a reconstruction of the sequence in which feathers first evolved and developed into the types found on modern birds.
Feather evolution was broken down into the following stages by Xu and Guo in 2009:<ref name="xu&guo2009">{{cite journal | last1 = Xu | first1 = X. | last2 = Guo | first2 = Y. | year = 2009 | title = The origin and early evolution of feathers: insights from recent paleontological and neontological data | url = | journal = Vertebrata PalAsiatica | volume = 47 | issue = 4| pages = 311–329 }}</ref>
# Single filament
# Multiple filaments joined at their base
# Multiple filaments joined at their base to a central filament
# Multiple filaments along the length of a central filament
# Multiple filaments arising from the edge of a membranous structure
# Pennaceous feather with vane of barbs and barbules and central rachis
# Pennaceous feather with an asymmetrical rachis
# Undifferentiated vane with central rachis
However, Foth (2011) showed that some of these purported stages (stages 2 and 5 in particular) are likely simply artifacts of preservation caused by the way fossil feathers are crushed and the feather remains or imprints are preserved. Foth re-interpreted stage 2 feathers as crushed or misidentified feathers of at least stage 3, and stage 5 feathers as crushed stage 6 feathers.<ref name=foth2011>Foth, C. (2011). "On the identification of feather structures in stem-line representatives of birds: evidence from fossils and actuopalaeontology." ''Paläontologische Zeitschrift'', (advance publication) {{doi|10.1007/s12542-011-0111-3}}</ref>
The following simplified diagram of dinosaur relationships follows these results, and shows the likely distribution of plumaceous (downy) and pennaceous (vaned) feathers among dinosaurs and prehistoric birds. The diagram follows one presented by Xu and Guo (2009) modified with the findings of Foth (2011).<ref name="xu&guo2009"/> The numbers accompanying each name refer to the presence of specific feather stages. Note that 's' indicates the known presence of scales on the body.
{{clade| style=font-size:80%;line-height:70%
|1=[[Heterodontosauridae]] (1)
|1=[[Thyreophora]] (s)
|1=[[Ornithopoda]] (s)
|1=[[Psittacosauridae]] (s, 1)
|2=[[Ceratopsidae]] (s)
|1=[[Sauropodomorpha]] (s)
|1=''[[Aucasaurus]]'' (s)
|2=''[[Carnotaurus]]'' (s)
|3=''[[Ceratosaurus]]'' (s)
|1=''[[Dilong]]'' (3?)
|2=Other [[Tyrannosauroidea|tyrannosauroids]] (s)
|1=''[[Juravenator]]'' (s, 3?)
|2=''[[Sinosauropteryx]]'' (3+)
|1=[[Therizinosaur]]ia (1, 3+)
|1=[[Alvarezsauridae]] (3?)
|1=[[Oviraptorosauria]] (4, 6)
|1=[[Troodontidae]] (3+, 6)
|1=Other dromaeosaurids
|1=''[[Sinornithosaurus]]'' (3+, 6)
|2=''[[Microraptor]]'' (3+, 6, 7)
|1=[[Scansoriopterygidae]] (3+, 6, 8)
|1=[[Archaeopterygidae]] (3+, 6, 7)
|1=''[[Jeholornis]]'' (6, 7)
|1=''[[Confuciusornis]]'' (4, 6, 7, 8)
|1=[[Enantiornithes]] (4, 6, 7, 8)
|2=[[Neornithes]] (4, 6, 7, 8)
==See also==
* [[Pinioning]]
==External links==
* McGraw, K. J. 2005. [ Polly want a pigment? Cracking the chemical code to red coloration in parrots.] Australian Birdkeeper Magazine 18:608-611.
* DeMeo, Antonia M. [ ''Access to Eagles and Eagle Parts: Environmental Protection v. Native American Free Exercise of Religion'' (1995)]
* [ Electronic Code of Federal Regulations (e-CFR), ''Title 50: Wildlife and Fisheries PART 22—EAGLE PERMITS'']
* [ U.S. v. Thirty Eight Golden Eagles (1986)]
* [ Mechanical structure of feathers]
* [ Documentary on the evolution of feathers]
* [ Lecture notes on the avian integument]
* [ U.S. National Fish and Wildlife Forensics Laboratory's Feather Atlas]
* []
{{Use dmy dates|date=September 2010}}
[[Category:Feathers| ]]
[[Category:Bird products]]
[[Category:Bird anatomy]]
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Reason: ANN scored at 0.985007
Reporter Information
Reporter: JimmiXzS (anonymous)
Date: Friday, the 14th of October 2016 at 02:16:07 PM
Status: Reported
Tuesday, the 6th of January 2015 at 08:37:22 AM #97565
sally (anonymous)


Friday, the 14th of October 2016 at 02:16:07 PM #106527
JimmiXzS (anonymous)