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==প্লুমেজ (Plumage)==
চৰাইৰ প্লুমেজ অৰ্থাৎ পাখিৰ ৰং, বিন্যাস (arrangement) আৰু সজ্জা (pattern) নিয়মীয়াকৈ সলনি (moult) কৰে৷ প্ৰজননৰ পিছত চৰাইৰ প্লুমেজ সলনি হ'লে ইয়াক 'non-breeding" plumage বুলি কোৱা হয়৷<ref>{{Cite journal|last=Humphrey |first=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://elibrary.unm.edu/sora/Auk/v076n01/p0001-p0031.pdf |format=PDF |issue=1 |jstor=4081839|last2=Parkes|first2=K. C.}}</ref> সাধাৰণতে প্ৰয়ভাগ চৰাইৰ ক্ষেত্ৰত 'Moulting' বছৰেকত এবাৰ হয়৷ অৱশ্যে কিছুমান প্ৰজাতিৰ ক্ষেত্ৰত ই বছৰত দুবাৰ আৰু ডাঙৰ আকাৰৰ মাংসভোজী চৰাই (birds of prey)ৰ ক্ষেত্ৰত ই কেইবাবছৰৰ মূৰত এবাৰকৈ হয়৷ 'Moulting' patternsৰ varyপ্ৰক্ৰিয়া acrossপ্ৰজাতি species.ভেদে Inভিন্ন passerines,হয়৷ [[flight feather]]sপেচ্ছেৰাইন are(passerine) replacedঅৰ্থাৎ oneপেচ্ছেৰিফৰমিছ at(Passeriformes) aবৰ্গৰ timeঅন্তৰ্গত withচৰাই theসমূহৰ innermostডেউকাৰ primaryপাখি being the first. When the fifth of sixth primary is replaced, the outermost tertiaries begin to drop. After the innermost tertiaries are moulted, the secondaries starting from the innermost begin to drop and this proceeds to the outer feathersসমূহ (centrifugalflight moultfeather). Theভিতৰৰ greaterপৰা primaryএডাল covertsএডালকৈ areসৰিবলৈ moultedআৰম্ভ inকৰে৷ synchrony with the primary that they overlap.<ref name="pettingill">{{Cite book|author=Pettingill Jr. OS|year=1970|title=Ornithology in Laboratory and Field|isbn=808716093|publisher=Burgess Publishing Co}}</ref> Aহাঁহজাতীয় smallঅন্য numberকিছুমান ofচৰায়ে species,আকৌ suchএকেবাৰতে asডেউকাৰ ducksগোটেইবোৰ andপাখি geese,সৰায় loseআৰু allকিছুসময়ৰ ofবাবে theirউৰিব flightনোৱাৰা feathersহৈ atপৰে৷ once, temporarily becoming flightless.<ref name="debeeretal">de Beer SJ, Lockwood GM, Raijmakers JHFS, Raijmakers JMH, Scott WA, Oschadleus HD, Underhill LG (2001). [http://web.uct.ac.za/depts/stats/adu/ringmanual.htm Web.uct.ac.za] SAFRING Bird Ringing Manual.</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=119–24 |doi=10.2307/3677029 |issn=09088857 |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=172–78 |url=http://elibrary.unm.edu/sora/Auk/v071n02/p0172-p0178.pdf|format=PDF}}</ref> The general pattern seen in [[passerine]]s is that the primaries are replaced outward, secondaries inward, and the tail from center 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|accessdate=20 October 2007}}</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=470–80 |doi=10.1086/515854 |pmid=9237308 |month= July|issn=0031-935X}}</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]] ▼বাহ সজাৰ আগে আগে প্ৰায়ভাগ মাইকী চৰায়ে পেটৰ পাখিবোৰ সৰাই বুকুত এটা অঞ্চল পাখিবিহীন কৰি তোলে, এই অংশটোক '[[brood patch]]' বুলি কোৱা হয়৷ সেই অংশত তেজ চলাচলৰ বাবে ষথেষ্ট ধমনী থাকে আৰু ই চৰাইজনীক উমনি দিয়াত সহায় কৰে৷ <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=470–80 |doi=10.1086/515854 |pmid=9237308 |month= July|issn=0031-935X}}</ref>
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=Behavioural Ecology |volume=16 |issue=1 |pages=89–95 |doi=10.1093/beheco/arh135}}</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|last=Shawkey |first=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=345–49 |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://elibrary.unm.edu/sora/Auk/v103n04/p0835-p0835.pdf|format=PDF}}</ref>
▲[[File:Red Lory (Eos bornea)-6.jpg|alt=Red parrot with yellow bill and wing feathers in bill|upright|right|thumb|[[Red Lory]] দেহ চাফা (preening ) কৰি থকা অৱস্থাত]]
চৰাইৰ পাখিসমূহক যত্নৰ প্ৰয়োজন৷ সেয়ে চৰায়ে নিয়মীয়াকৈ দিনৰ প্ৰায় ৯% সময় পাখি সমূহ চাফা কৰাত ব্যয় কৰে৷ <ref>{{Cite journal|last=Walther |first=Bruno A. |year=2005 |title=Elaborate ornaments are costly to maintain: evidence for high maintenance handicaps |journal=Behavioural Ecology |volume=16 |issue=1 |pages=89–95 |doi=10.1093/beheco/arh135}}</ref> ইহঁতে ঠোঁটৰ সহায়ত পাখিত লাগি থকা ধূলি বা বস্তু আঁতৰায়৷ তাৰোপৰি 'uropygial gland' এ নিঃসৰণ কৰা আঠাজাতীয় ৰস (waxy secretion)ৰ ব্যৱহাৰ কৰি পাখিৰ নমনীয়তা (fexibility) অটুট ৰাখে আৰু অন্যান্য ক্ষতিকৰ অনুজীৱসমূহৰ পৰা প্ৰতিৰক্ষা দিয়ে৷ <ref>{{Cite journal|last=Shawkey |first=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=345–49 |doi=10.1111/j.0908-8857.2003.03193.x |last2=Pillai |first2=Shreekumar R. |last3=Hill |first3=Geoffrey E.}}</ref>
===উৰণ ক্ষমতা===
অন্যান্য মেৰুদণ্ডী প্ৰাণী সমূহৰ পৰা ব্যতিক্ৰমী বৈশিষ্ট্য হ'ল প্ৰায়ভাগ চৰায়ৈ উৰিব পাৰে৷ উৰণ ক্ষমতা প্ৰজনন, খাদ্য আহৰণ (feeding) আৰু ভক্ষক (predator)ৰ পৰা ৰক্ষা পোৱাৰ বাবে ব্যৱহৃত হয়৷ <ref name = "Gill"/> ডেউকাৰ আকাৰ আৰু আকৃতিয়ে চৰাইৰ উৰাৰ ধৰণ নিৰ্ণয় কৰে৷
Most birds can [[Flying and gliding animals|fly]], which distinguishes them from almost all other vertebrate classes. Flight is the primary means of locomotion for most bird species and is used for breeding, feeding, and predator avoidance and escape. Birds have various adaptations for flight, including a lightweight skeleton, two large flight muscles, the pectoralis (which accounts for 15% of the total mass of the bird) and the supracoracoideus, as well as a modified forelimb ([[wing]]) that serves as an [[airfoil|aerofoil]].<ref name = "Gill"/> Wing shape and size generally determine a bird species' type of flight; many birds combine powered, flapping flight with less energy-intensive soaring flight. About 60 extant bird species are [[Flightless bird|flightless]], as were many extinct birds.<ref>{{Cite book|last=Roots |first=Clive |year=2006 |title=Flightless Birds |location=Westport |publisher=Greenwood Press |isbn=978-0-313-33545-7|pages=}}</ref> Flightlessness often arises in birds on isolated islands, probably due to limited resources and the absence of land predators.<ref>{{Cite journal|last=McNab |first=Brian K. |month=October |year=1994 |title=Energy Conservation and the Evolution of Flightlessness in Birds |journal=The American Naturalist |volume=144 |issue=4 |pages=628–42 |doi=10.1086/285697 |jstor=2462941}}</ref> Though flightless, penguins use similar musculature and movements to "fly" through the water, as do [[auk]]s, [[shearwater]]s and [[dipper]]s.<ref>{{Cite journal|last=Kovacs |first=Christopher E. |month=May |year=2000 |title=Anatomy and histochemistry of flight muscles in a wing-propelled diving bird, the Atlantic Puffin, ''Fratercula arctica'' |journal=Journal of Morphology |volume=244 |issue=2 |pages=109–25|doi=10.1002/(SICI)1097-4687(200005)244:2<109::AID-JMOR2>3.0.CO;2-0 |pmid=10761049 |last2=Meyers |first2=RA }}</ref>
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==আচৰণ==
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