Origin Of Birds PDF

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Scanned with CamScanner 1. ttÏri‹‘IlI nItLÏ AtÜ€ïFClt|, tgçrçgtyjg) f'Iying hitds. Usu1Ilysmnll.‹'. d. Barbs interlo k‹z barbulcs and hap¡Cyjq Irregular, continuous. Regular,separaed by„„, Absent or irregularly arranged. Regularly ged i3 ( manncz Absent. Present. d'ell developed. Poorly developed. Absent except kiwi. Present. 12. Rharnphotheca Compound, composed ofseveral separate Usuallyundivided, any$ pieces. compound inAlbatrm. Usually absent. Present. i 4. Nature of skull Large and strongly built. Srriall, light and fragile. i5. SUI sumres Remain distinct fora long time. Disappear very early. 15 T pe of skull Dromaeognathous orpalaeognathous. Neognathous, never Rio» gnatbous. IT. Çuadrate Y-shaped bone, articulates with the squamosal Never Y-shape‹l, arlicu Vestigial or absent. yroccss Present. 27. Coracoid gpd rativelysmaIl, aad fï @t M &tuse scaPula Scanned with CamScanner Scanned with CamScanner  th "ds nH›ryf›‹›lf7gical characters h‹›w in2 )iad required lht›sc groujjJ. [§ thu“ cnUmic.5 ürc rcmr›v , the I hcrcr‹›rc, in thu ttf'CttS wh ÊD ÏhCÏ‘ werp t//-tcstriaI prcJat‹›rs and c‹›mpct " ' ‹he°,* ,. t}jg y gnfi ’A]I f7Ï" (Ï1C (tlTïC, t}jUy, ‹›fr ›‹›d. The abo o vcw pupounJcU by Romzr is alec r.ttiIc t,r‹›tIirCl11cn’ ‹listribution ‹›f (h0 fät1fCS !! oï them li VV Ifl lhc fcgions thai mee from formld8blC bifd en ice On the ground. back to the carly Ccnozcic Era. ccrtain ratites can be traccd ncognathous birds also lived then. There might have birds and early mammals for the conquest of the «› iiti‹›n 2t thaltÏÏT}c bctwÜ8» «s»i› sec ›JlOfl theGovernment of New Zealand has set ”Gta **°'°kiwix fC“‘mon brown kiwij, Ayterx hoasti e® *Rteryx has three species, (8° !*ï"S OtÏd klWÏ) and Aple x oy 73 (little spott ' i) ORIGIN OF BIRDS dunng kfesozoiccra. ThC S cl group of ertebmtes w aclual documentaiy Pcordao hich have evoïved f?Of0 träM >rmed into birds b thti stages Showing how such repi› *’ a transit bPcguse of thenon-avaiisbility of abillldant avian fossils- ptilcs and a vcs is fo two ssils represented by APchaeopter) z and Nrc6‹f undoubbd y,These combine t j» features,CO that the reptiJj OMgjy of reptilian fea *S btrdsiS ObVious. Scanned with CamScanner  : s 6räIAccount t ¿|1ljlÏnI1 nltttül‹›r i8 ytl ttj [jg [ l|jj ], '[\yj it‹tiui” ‹ “ I yl›t›ll cli*til it‹1 *Rlt›r I r«RYes’ wftith f‹›rmctl ihc link f›ctwccn tgj {}g}t0¥’fÏ0, tt10 tt11ÜC9lI”g| 1›Ir‹l wns nn arh‹›rcal fniir-lcggcd paracfiuling animal -n ê’“ ‹›l”I ‹*tI!c ni'd ^trcngIl!*itiig t›f wiiig mii.sclcs. In nther flying animals like bats with F‹itngiixn, hi* I indlin›hs arc in=‹iFacitxtc‹l fnr walking, whereas in birdg, EEC HOO )f lÏlllt IÏIC ' Ü£OhVCS' W8S fl CUfSoiial long-tailed, bipedal $q about and leaped along the ground with iheir slrong hindlimbs, flapping their \r as an aid to lncfCgS0d spc«d. The forelimbg which ware the wïngs became by thedcvelopment of scales in the hinder part of the arm and the scales became tofonll quill feathers. r** suggests that the ‘Proaves’ should have been an arboreal form with four legs, the modified for springing, and forelegs for climbing and steadying the body aftera egs heidi thers yt quillfea developed along the hinder aspect of the forelimbs and the tail which plflldÏ to buoy up thebody intheair. The transformation of the forelimbs into wings by thedevelopment of bipedalism. the suggests that the Proaves should have been an arboreal tetrapod with backwardly t‹dfeathers ifl all the legs, both sets serving as parachutes in gliding. This view is supported $,g cahons of tufts of feathers in the hinder aspect of the limbs of Archaeopteryx. cr sory is of the view that birds havea dual origin, some have evolved from cursorial a oaa som arboreal ancestors, which will be seen to bea compromise of several theories. l'tesently the origin of birds is considered mainly on two lines diphyletic origin and ' pAylehc ongin. èipiyletic Origin of Birds fire earliest known fossil birds include both flying [Archaeopteryx, Ichthyornis} as well n ligâtless (Hesperornis, Diatryma) types. The recently extinct Moas andElephant birds were dz âigbtless. The most primitive living birds or Ratitae (Ostrich, Rhea, Cassowaiy, Emu and I) aDd Penguins are also flightless. This led some authors, notably P. R. Lowe, tobelieve in (two-lines-of-descent) origin of birds. They maintain that the flightless and flying $day have descended from flightless ancestors. According to Lowe, the present-day birds were never capable of flight, and their wings are not degenerate now, but betier any time in their past history. «phy@t!c Origin of Birds the legs are well-developed and powerful, the wings vestigiol, and the feathers Buta recently discovered fossil of Eleiilidr‹›rni«,a prubeble ancestor of the prcsent- Ch from the Eocene of Switzerland, shows closer nlfinities io flying forms then does y o Strich and posesa serious bloW IO the concept of diphyletic origin of birds. palaeontologists believe that the Curitliltae are more priinitive. Presuniably the ffomdy|ng aneestors but rcadaplcd too tc rst iiin oJe of lifè in arcas with *od and few competitors or cnemies. 2’b aeceplc d view toduy maintains have$ monophyletic (one-line-of-desCCnl) Oflgfn, i. , all birds havc tvolveJ kom a 3tor, perhaps close toArchaeopteryx. Accordingly, the flighlless birds huve evolved *m flying ancestors. The weight of the knowne id nce nlso faVours this view. Scanned with CamScanner  LII RG N 0 with ihc chnngus from tetrestrial tp ggpjal ÏIOW C0ld of birds 1.Sä -bl walg-b1ooded gy¡ng bÏF4 are insufficiently Jy dssjc bed. We krioW hoihing although inlegtediatc structutes betwe cvolution of (py}, Wc, p( cotlfigfl, dO HOt kfloW feathen arep resumCd thB( the anccstors wetc @ , evolved in the fÏtllflfÏ Ï)f tO aciive and pussibly wann-blWCd ttltd fcathcrs that the tail probably lo fovide sta§j¡$ hody heai.Leter. the feethers enlngcdonthc ümbsand nidi eniaiy gliding from branches. l Different theories have beenproposed to explain the origin of flight in birds, staq¡d$p eithera terrestrial, bipedal and cursorial ancestor (Nopcsa) or an arboreal ancestot (£g $ Stciner. iteebe, etc). of eunorlal origin of flight. Nopcsa has advocated the cursorial orig¡ty According to him, the proaves was a running reptile. While running fast on the pp is reptile lifted the forelimbs off from the ground. The scales over the margin of the linit becnme expanded as feathers. Nopcsa believed that birds arose kom bipedal dinosaur-like rtjq which used to run on the ground by hindlimbs. According to his theory, the ancestors of £bâ » ere long-tailed, cursorial, bipedal animals. They were fast runners who leaped on Weir smr hindlimbs and flapped their forelimbs in air to help them along, as do many modern binls $ii run fast Gradually the forelimbs enlarged due to fraying out or elongation of ScaleS f0fiuxq quill-feathers through the process of mutation and selection. In the end, the forelimbs betaai organs of flight or wings rather than accessories to rapid running. Scanned with CamScanner  (y(ągj: Oenerai Accoynt „ l'his ve i›nlf€'c.9. ț‹› t›Ihct lrcc4, lİk0 ț|țp. yy, rrr›m >hirh ihcy has J”hi has in Iii‹i‹Ilin he *hích isnifes ir.›t tluriny ih h ilì0 fłYû.8 nnd fłlg‹y dtirin Parachut ing from ‹jhlc to gtIgg‹ïn Ilïc animal In flight.The * 'g*ś n‹i eventuallycnnvcrt‹d țtł11C fCalhers 0 thC hindlimł›s in lhc modern b‹td, Thus. nigh W vanished and iw ! nq nn nvłg‹ th , ai iaïiis tIint the hlndliinbs I the ancestor were İflčd ÊfrF xpnngin. while Ihc i.mcd for climbing «nd balancing the body aqgt B )gã İfł (ke air. theory of origI orni,hi. advan a cornprnmiw mmą dualoJgin of birds. Believers in the dual o*8in ced m ti from arboreal and others from cursorial ancestors. of birds aintain that wme j. pIvi g theory of orígln of fIiget. Neumann regarded the pr‹›avcs as aquatic rcptilc ¡p pi hihavc started in connection WİtÍl SOilring over the water duńng divingI r ß›hcs. BIRDSARE GLORIFIED REFTILES ' Nearly a century ago, T.II. Ilualey called birds ‘glorified reptiles’, thereby meaning t¡rds haveevolved from some reptilian ancestor and that they are better evol›‘ed in their anÎsatÍOü. The evidence from comparative anatomy, embryology and palaeontology with fossil lctaeopteryx as the transitional form suggests that bird isa highly pae reptilian ancestor. Tàe steps and the impulse under which evolution of birds took place froma reptilian set arc not properly understood at present. Whatever may be mode anddirection of origin of lR ßomancestral reptiles, the modem birds showa marked superiority over their reptilian ancestors. Some of the main changes leading to the glorification or superiority of birds over mptilcч m as follows: reptiles are generally sluggish, cold-blooded (polkłlothernious) and earth-boun‹t active, warn-blooded (homoiothermous) and alert, having more łiJe In J$r living creature. They havea higher rate of metabolismand correlated carefully body temperature. They arewarm-blooded and due to this they are equally acti›’2 bra ut the yggp. ShOWa more rapid locoiriotion due to power of flİghl. perhaps also the most the animal kingdom. * &YeIopment of avian feathers fromrep«Jtaj2 SCalflS İS dctinİtely on < zt k« ROI birds to Ry. The insulating fu«th ”1 vclecity or height. Scanned with CamScanner  tyi,d ): aaneral AccoUf'Ï\ a lan‹llng; I!›C ground ‹›r ›q t»‹» rk‹iblc rif flibht ‹i'r ”’ä° "*nB- r ^, *°"h a» cÏfclcl without 1 2 EFFECTIVE OR DOWI‘4STROKE 4 5 6 RECOVERY OR UPSTROKE A B e p Modes of flights in birds. A-Gliding (swift); B-Soaring (albatross); C—Floppinq (duck); D—Hovering (humming bird). 3. Flapping. This is most common orordinary mode offlight (Fig. 28.4C). All birds fly p Mapping their wings up-and-down. Each flapping includes an effective downstroke and a every upstroke of the wings. To start with, the wings are held vertically and fully spread. In âi downstroke, they move obliquely forward, downward and backward, their distal portions dcl upwards. Thus, there is both lift and thrust. In the upstroke, the wings are partly folded adHir primary feathers spread out for the air to slip through, thus making it easier to liR them. move up and backwards. As a net result, the bird will be propelled forwards and sustained &e air. The pigeon flies by flapping method. The flight includes the quick lake-off by jump *IEpping of wings in downward and backward stroke, which propel the bird forward, and NJ fofWard and upward movement of recovery stroke, this is done by bringing back the ring & *he to the resistance of the air. The downward stroke of wings works asa lift force acting i d1. The lifi force is proportional to the speed, and the requirement for sustained flight in !f lS that the bird should have sufficient speed to generatea lift force equal to its wtight. OK air over the upper surface of wings reduces the pressurc andprovides a ponion of Bytilting the wing thepressure on the undetside can be increased. Pigeons cm bent W!DS fltleast eight times in one second. / Hoverin g. This isa p eculiar kind of fioppingflight. Support of wci{}ht without hcri2oItt&I of encri,y than forward flight and thelarE< S tequires very muchg reatcr consumption used fot shott times by weigh only 80 gm. Thc principlu involvcü is also that t;ips horizont& ‹3 tate-off and landing( eIss-gogh, t173). LiÏÏ the body, hovering is achieYeU " * s ond since the wing beat ltt P ingbirds 2H.4D). In this way ihe hum» y holding the body beat 2* o in the air or even movc backwards. The wings ‘S BOOtjmesa second. Scanned with CamScanner  anoroate gq °’°*7 pIAË AD §P7AT IOH OU BIRDS FLIGHT OR AE ’ › Iïird. i›..’ ii›. ''' ':' '"""'"'"' """‘" ""’ t ‹›r {grr«strial modc oÈti$g |jçxiclç acri iI !t\‹›d !”” '*’*'' i”t’!t kiwi, cl\jnfjy Il1t'if ai›tl flipJ›= lucy othcr cf birJs i i ‹,< = =r" ".'i"1› “”"““”’“” ” *’” }y) ¡jCjjj {jCS flH€) fl)lTlO5{ tjyQ OfgâHS for m it !/' i›i'‹›i‹'vy' ,!*”” cxir:› crgy with provis'oH ËOf high power, ci› volant !i/C OU birds can be sadic4 y, ûtorphologicalAdaptations i› r ant fiight or volant adaptations : j. Bods rcntour. a must for aerial life, SO, to minimise the d ihe body of birds isfusiform or spindle-shape and it lacks rcsistance in theattainment of speed in air like fish in thg dater. Compact bod›: Their compact body is light and strong dosrsally and heavy » hich s‹i in maintaining equilibrium in the air. The attachement of wings high upon the troy thehut position of light organs like lungs and sacs, and low central position of heavy musc q, ›i. um md diçesti›e organs below the attachment of both the wings and consequently 10s cease of gravip are other morphological facts of great significance. 3. Bods’-coi’ering of feathers. Body of all birds is covered by special integumentap dern a'.ii es called feathers. Feathers are diagnostic of birds, since no other group of animal 1:in dom has m er developed them. Feathers have following advantages for birds (a} The smooth, closely fitting and backwardly directed contour feathers make the body streamlined helping them to pass through the air by reducing lhe friction to the minimum. Ih I The feathery covering makes the body light and at the same time protects from ä* kazards of en›’ironmental temperalre. le! The feathers holda considerable blanket of enveloping air around the body and6d ranch to its buoyancy. Bd}TÏlg non-conducting mobile neck *f ng of feathers insulaas beak OSI of hCdt WÏlich eriables streamlined spindle- tf}c biFd fU endure intcnss shaped body ! 9*t if\sulatlng foreliN*! Îeäth6fÿ coverlng odifed I l/”0“dlh0/S ïjf ' in « ’ »!‹»a *++r1cu for ht bUt5 ’* into have f›earlng anJ rectrices bIpgç|g| — '' ’* lTloIIon FI 28./ @g ‹ «hoWlng the streamlined body Of bird Scanned with CamScanner  l Account ș (glrd+) genera of flight. Theseoiyanz hivo jtlUšûÎC9, florУcS, bIt1cd wlnye k,Duriny m.zł lli ° ^"»ln ’=”!! x !› ‹ ih° i‹i ‹›r ih° »‹a›. hui‹ н»t surface 8rC8 ,ę ‹** „» çig''-f sü ". -h* ^ '° ° T' van '° ‹ f '* n isi »з ».»ii»«». the air la fliyht. Theni ‹tńkln8 4t ‹›r tlte birtÎ III üit. Tl1C țial1lcü|at sltgțje tț(' ț(jț Wİhğ, Wllh thlck zt«my )cadIny c‹lyc, yÏ’BCe Bhd cOflCßVe ltjWCr èU\-Ï’ tt, below, wiih minin um turbulence behinJ. d yț} flight. +«d дpJle necłtand head. The transfomisllon of foreliinbs intu wings i0 July c‹xnț?ttnyAlcÜ psetlcg Of bQäk or bill used forfeeding, nest buildìry, prccnlny, unJ ‹offence anJ defence. youth ‹s æwn outintoa horny beek which y$jjoU5 othefiaCtivities such as nest buildi^B F iztg, etc., which arc mrmstìyd‹inn 6y í other animals. The neck in bitds is also very long and flexible fa the movement forvarious functioni. ç, Ø¡pedał locomotion. As attterior part of the body of birds htcomcs concerned with tye posterior part of body becomes modified for movement on land. Per loc‹rneiínn on and to support the entire body weight, the hindlimbs occupya icmewhsi Interior )jggtğgg Oß tÏt6 trunk and become more stouter in case of rattles whlch are running blnfn. 2, Perching. The hindlimbs ofa bird are well specialised for вn nrborcal life. Theír muscles developed in sucha manner that whena bird sita on a branch of the tree, the toes ełmc d íhe twig automatically. This happens due to so called perchtng mechanlim. When tht lúd settles on the branch ofa tree, the legs are bent and put the flexor tendons on the stretch. kä die exertion of the pull, the toes are bent spontaneously around the perch.A bird can gø в step in this position without any fear of falling off. 8. Short tail. Thв short tail of a bird bearsa tuft of long tail feathers or rcctrleeo, which Arced out ina fan-like manner and serve asa rudder during flight. They also assist in steering, lifting and counterbalancing during flying and perching. $. Anatomical Adaptations 2/ring birds have following anatomical modifications for volant life: 1. Fligbț muscles. The action of the wings is controlled by the flight mu4slea which are developed, weighing about one-sixth of the entire bird, while the mußclßS 0( tÍle bøtk $restly reduced. The muscle fibres comprising the flight muscles arc of suialtd type and *Mcularİsed to withstand fatigueness afler prolonged activity. The wings are depressed by pectora\is œajor and etevatcd by pectoralls minor. Otł›cr muscles aro amall aod aboVe muscles in their functioning. Llğ§tness and rlgldlty of endoskeleton, The skeletal framework of flying bitds is very lightly built OU the "ho)low-girder principle“. Mosl uf the bunc› s‹< atlcs, filled with air sacs endprovided witha secondary plaxicring to n›ako thrm rígiã. Sum 0ø İ8 Sking inbones of birds,Further skeletal framework becomes compact, cvntmlised tuz!on of bones. Endoskclcton of bir4s th\t9 OOftłßtn» the fullU\è'íng (‹zz, tkul) bones are pajłCr-llkC thin and show u leniency towards (ho 'w‹bcr, bonke finnly fustd with each oihot. The poatoriur portion §8Tt O{ YgftCbfg} COlUfTlft. Êk8İofl OI* V0/tCbFB*î ° '^ °*i*ï e «ïr. w‹ ^ ïn»i° '=°*°° °r ‹h°°°i ńbs hølp inp Scanned with CamScanner 536 viclcs fused with intcfClaviC i‹›, I›y resist thc inWard qp$ jbj] i}y and birds (iii) 'l'lic ,t.„ii,‹,› i ‹i t°' f ih body r‹›ri» li‹›„ «r tyț: »tyIc has8shistedstabili lit1t IL ț i ) Slriaiiiiii tH l'rci'* ii ¡r witl›‹›ut i kccl in running birds, (vj) The Hrs İtiil t› I’ vcrtcbrac) not onlySUpport« th« vci’tc1u‘ac f*w t5 the łTCCt of shocks a» thc is valki g, *ul *lso counlcrac ,syiii{зli\Si$ t›f isc1›ia and p ubis permits laying of large ilÍJ. distal I:irsals with thernetataFSals tO forma tarsometatar sus, strengthen fire lower cnd Of tibia to forma tibiotarsus, help to for bì¡icdal gail. for the attachment of ț› iii) The skeleton of forelimbs is completely modified (tgiiiiç-s) and flight muscles. Thereare only three digits, which are morc or less fiised. 3. Digestive system. The rate of metabolism in birds is very high, so the foodrequired, arc great and digestion is rapid. Most birds are veryselective in their diet and accordingly t§p beaks arc variously modified. Further, because undigested waste is minimum andis imm‹diii‹ › got rid of, consequently the rectum becomes much reduced in length and never storesÁ undigested food. The ill-development of rectum of flying birds indicates towards the fact that ât flying animals cannot afford to bear the weight of faeces. The absence of gall bladder in 6é$ minimises the bodyweight to some extent. 4. Respiratory system. As a flying bird requires great and sustained power, therefore, is respiratory system is specialised ìn sucha fashion that the food is Combusted (oxidised) raçiój and completely to liberate large amount of energy. To meet the extensive rate of metabolite greater amount of oxygen molecules is needed by the body tissues. For this purpose, the dm - compact, and inelastic lungs are supplemented bya remarkable system of air sacs, which * out from lungs and occupy all available space between internal organs, even extending l0 lò* cavińes of hollow bones. The air sacs primarily reduce the specific gravity of the bird Min also facilitate complete aeration of the lungs. The avian lungs are aerated twice at each bftá* which secures perfect oxygenation of blood. The air sacs help in regulating body by iiitemal perspirati oll. Further, insertion of air sacs in between the flight muscles lİkC reduces mechanical fiction and increases the mobilityill muscular action. 5. Circtilatory system. Rapid metabolism r which can bc achieved by an efficient equires large oxygen supply to the circulatory system. Accordingly, avian her '* sized, four-chambCfed, powerful and efficłent.Duc to anddcoxygenated bloods rcpц¡øCOtTł{31gtG1y scparat double circulation in it, the d.F lrther, red blood cells of birds large amount of haemoglobin which isresponsible for QUİCkand perfect aeration of łiÓd} >olleys in the winicr occur in nanny lndifin and * species ‹luring summer mit,o o (rom planes to c */ feet abovc sealcvcl alld fc*tUiT1 te yluncs ot\ the food-cock, Bush chat and Srulnpiu: ‹l the trebes and coots of Andes in Arg0l1tJ/3+ Scanned with CamScanner  ttltlmayc ‹îËWi) l0W Çt8fYtïÏ ‹ f /t|tlCrn and willuwn. ynlklend lsland, anJ south une (Yit›1r li›r lil x€iI›y. 4, I artlal mlgraHnni. Many py igs, nuch en blue bird i afld fTlany bin)s of'a pn›iip of’ iiiigi:iioiy bii’J do lt›t.4«iaii› th‹»‹ »= /= ï°l i›'iyrnnt. hc=au c *h* birdsvisible in winter arc **(the s. Erratlr mIgratt«n. The erratlc, vagraüt. Irrcgular or wanderlng ers.at hliic M n›n. cuckeos, ihruilics and warblcrs. lu such birds, after breeding, ‹hr ‹›«n m«t m›y fmm their home todisperse in all directions over many or mil‹:s in search of feed and safciy from enemies. Sometimes hurricanestake thy g for a 2n0 miles auay from home seas and there they die either due to exha«iiip unknt›on shores. k Seasonal migration. Some ornithologists of temperate countries have classify birds according to seasons. Thus, inBritain, swifts, swallows, nïghtingales and cuckoos e $g tfiitori, because they arrive in spring from the south, remain there IO breed south in autumn. Some birds, such as fieldfare, snow bunting and redwing, are wlnter as ' arrive in autumn, chiefly from north, stay throughout the winter, and fly apain in spring. While some birds such as snipes and sandpipers are the birds ofpos J‹,m for slxxt time twicea year on their way to colder or warmer countries in spring and aotup Bcsides thèse kinds of avian migrations, following three kinds of migrations can alxib recognised in different birds: M Clime”De migrations occur asa result of daily or seasonal changes in the ct the environment. The well known north-south migration of many ducks and geese isi example of climatic migration, B. Alimental migrations occur asa result of food or water shortages and may ' C. G8fnttiC mlgFatlons result froma need to occupy some special region or 2* f‹r some part of the reproductive process. Most migratory birds perform gametic 'W"’ uoaes a night Inmigration °'* g * 's ii , iD flt lTlibfiâtOJ birds dÎ play following significan ** ' miss( migratory birds cither fly during dan! ” KDd mCtitdingly following /y i»ainly by day, such as crows, blackbirde, lt›ons, yelicanz,g »s , d«cks, »qg, snd birds. f‹xxJÎR theair as theytr»v»I. and swills caP* Thèse oAon tnivel in {IOCkS# çj floctuf»aI n›igran( Uljdcr tkc rotect ds, such as Bparrows, warblcrs, t/rushes, etc. Those birdsp re/er IO e›’ escays ‹h0)Ï’Cn9mies. B take *Ûg y 7OCUFe fcod dans ght. y flying at ni again at the apP* Scanned with CamScanner  gpą,):senerBl Account. *‹*minonly varic ftoni one ,i ^) migrate ßfXłUt one end It feWhundredfeet and I ohuut łl,0f8l feeÎ. while ł‹› '›‹o› tram ‹he Arctic 1.abnidt›t łu theedges a8ain returns ii› Ihc summcr to the coæt ab‹7lłt lhc oJft›c dist‹incc. Wh‹ic ¡y jçltlfłlü)f Of tl(ïtïtll }Î,O00 țtjțț South Afńca ^”’ ”II *al*uIulcd that 3,ŒXł million laмł hirds ”un› w tuA inca c.зch nutugttt and half of them 5UCCCcd in rctuming next spring Jltiiude of flight. SOlllC bİrds flyq«ic close tÊÏ the cgĘtÏł, whİle most routine migration.000 fact.of the eanh. Certa_iti smali land birds have been reported Io fly in feet altitudes. Further, some avian species even cross the Andes and tiiude of 2,000 feet or more. ,ą›øiș during migration. The speed or velocity of flight of migratory birds Maries to individual and species to species. It is affected by the speed of air and its has been reported that birds travel faster during migration than at any other seeds of certain migratory birds has been tabulated in the folloz'ing table: Fuo›rr SPEEDS OF BIRDs (AFTER PETTY, 1962). Distance.i -' 'Elapsed Õme (milei) of flight (Days).YSpeed of return to nest after being experimentally displaced. 1. Яmx shear water 3293 12.9 263 Jean albaEoss 3200 10.0 320 ' !. ß stotk 1404 11.9 118 tern 1081 5.0 216 ' íI‹mirg pigeon 1007 1.5 671 site swiít 1007 ).o 336 kg gull 870 ,¡ 212 o e porn to anot 1. km 8699 114 75 '%-hired shear water 6s35 ° 129 !lsd dowitcher 2299 20 y llow legs 1926 y B, with the speed ot”30 miles per źi+›graticn, mzxi«i sPre‹J r "corüed so bill fÎics witli the P Șd tif 3J Indian swil!»“) Siuari is about 170—200 fnİ* P** ratory birds +*”Y Ïł Illg day ora nİtțh( wilh #+ «rinkxn‹1 Food. Golden ploVPfS \q Ït0urg per day and xi«o txk rest ›+ Hudson Bay and OUth detinİtC JİtleS OÊ ëigh‹. The tfligfatoiT birdø 0||+w°*N ed by them may be the Name while golng g back or moy be Scanned with CamScanner  flow. In spring it takes place ll1lg North to South wfth thecoolw tn N‹›