pakshiyon ka pravrajan

pakshiyon ka pravrajan ya pakshiyon ka pravaas (Migration) paksheevijnyaaan ka bahut mahatvapoorn ang hai. unka yeh pravrajan, rituparivrtan ke samaan niyamit aur kramik hota hai aur yug-yug se yeh manushyon mein utsukata aur jijnyaaasa utpann karta raha hai, yahaaain tak ki red indiynon ne apne kaleindar ke maheenon ke naam pravrajan karanevaali chidiyon ke aagaman par hi rakha hai.

chidiyon ke pravrajan ke vishay ke maanya pandit laindsabaro taumasan (Landsborough Tomson) ne pravrajan ki vyaakhya is prakaar ki hai:

nivaasasthaan ka samay samay par baar-baar aur ekaantar disha mein badalna, jisse har samay jeevanopayogi praakrutik avasthaaeain upalabdh ho sakein, pravrajan hai.

bahut poorv aisa vishvaas kiya jaata tha ki jis prakaar kuchh stanapaayi aur urag sharad ritu mein thandh se bachane ke liye sheetanishkriyta (hibernation) mein chale jaate hain, usi bhaaainti abaabeel, kalavinkak (nightingale) aur koyal bhi sheetashayan karti hain. aisi dhaarana arastoo ke samay se hi chali aa rahi thi.

anukram

pravrajanavistaar tatha laabh

kaali cheel ka sthaanaparivrtan
hara - sthaayi nivaas
neela - sheetakaaleen nivaasakshetr
naarangi - ghosala banaane ka kshetr

ushnaraktata, pankh aur udaan ki adbhut shakti ke kaaran chidiyon mein sthaanaparivrtan karne ki kshamata ka vikaas bahut adhik hua hai. yadyapi anya praaniyon ki apeksha pakshi atyadhik sheet ya atyadhik ushnata donon ke prati sahanasheel hote hain, tathaapi sharad ritu mein jab bhojan ka abhaav ho jaata hai tab unhein baadhya hokar pravrajan karna padta hai, anyatha ve mar jaaeain. pravrajan ke dvaara chidiyon ko do pratikool rituon mein bhi do anukool kshetr praapt ho jaate hain. ek kshetr mein ve nivaas karti hain aur prajanan karti hai aur doosare kshetr mein bhojan tatha vishraam ke hetu jaati hain. yeh prakruti ka vidhaan hai ki chidiya pravrajan kshetr ke thandhe bhaag mein hi ande deti hain. ataev uttari golaardh mein unka maithunakshetr aarkatik uttari dhruv athva samasheetoshn kshetr hota hai, kintu dakshini golaardh mein iske theek vipreet, sheetakaaleen aavaas bhoomadhya rekha ke sameep hota hai.

praaya: pravrajan uttar se dakshin ki or hota hai, yadyapi kuchh pravrajan poorv se pashchim ki or bhi hota hai. pravrajan kuchh kilometer se lekar hajaaron kilometer tak ka hota hai, jaise kuchh chidiyaaain himaalaya ki adhik ooainchaai se utarakar uttari Bhaarat ke samatal bhaagon mein chali aati hain aur kuchh hajaaron kilometer sudoor dakshin mein chali jaati hain. sabse adhik door ka pravrajan uttar dhruveeya kurari (Arctic tern) karti hai. yeh pravrajan pratyek varsh do baar hota hai. yeh aarkatik ke sheetakaal mein dakshin ki or deshaagaman karti hai, sansaar ko paar kar dakshin dhruv anataarkatik mein greeshm ritu bitaakar pun: vaapas hoti hai. is prakaar jaane aur aane ki ek or ki yaatra mein lagbhag 17,742 kimi. ki doori tay karti hai.

pravrajan ka aarambh hone ke sambandh mein siddhaant

chidiyon mein pravrajan ka aarambh hone ke sambandh mein anek siddhaant praatipaadit hain. pravrajan se chidiyon ko nimnalikhit laabh hote hain :

  • sharad ritu mein uchch deshaantaravaale pradeshon se hat jaane ke kaaran thandh tatha toofaani mausam se raksha hoti hai,
  • sharad ritu ke din chhote hone ke kaaran prakaash kam samay tak praapt hota hai. isliye bhojan ki talaash ke liye jo kam samay milta hai tatha usaka niraakaran ho jaata hai,
  • jal ke jamane aur jameen ke himaachhaadit hone ke kaaran bhojan ki jo kami ho jaati hai usaka niraakaran ho jaata hai. greeshm ritu mein pun: uchch deshaantar pradeshon mein laut aane se pakshiyon ko tatha upayukt
  • kam dhani vihang aabaadi wala kshetr prajanan ke liye upalabdh ho jaata hai,
  • un dinon, jab unhein apne aur bachchon ke liye adhik aahaar jutaane ki aavashyakta hoti hai, aahaar ki talaash ke liye lamba aur prakaashamaan din praapt ho jaata hai aur
  • vasant ritu mein foolon mein laganevaale vaanaspatik keeton ki prachurata hoti hai.

chidiyon ka pravrajan pakshi ki ant: aur baahya donon hi uttejanaaon par nirbhar karta hai. prayogon se prakat hota hai ki baahya uttejanaaon mein se din ki avadhi mein parivartan pramukh hai ; ant : uttejana prajananaangon se utpann haaramon dvaara praapt hoti hai.

pravrajan ka lakshyasthaan kaise nirdhaarit hota hai

pravrajan ke kuchh gyaat maarg

pravrajan ka lakshyasthaan kaise nirdhaarit hota hai aur chidiyaaain is gantavya sthaan ka raasta kaise maaloom karti hain, inka anek prayogon aur prekshanon se par bhi abhi tak santoshajanak uttar naheen mil saka hai.

sharatkaaleen aavaasakshetr mein sharad ritu bitaane ke pashchaat vasant ritu mein prajanan kshetr athva greeshm-aavaas-kshetr mein vayask naron ka pratham punaraagaman hota hai. iske baad vayask maadaaeain aur ant mein avayask chidiyaaain pahuainchati hain. kintu sharad mein yeh kram ulat jaata hai. pratham avayask pakshi aur maadaaeain dakshini yaatra ke liye prasthaan karti hain aur baad mein vayask nar. dakshin ki yaatra bade itameenaan se auair sthaan sthaan par ruk rukakar hoti hai. chhote bachche athva kishor, jinki umr kuchh hi maheenon ki hoti hai, kaafile (vanguard) ka pathapradarshan karte hain aur vayask baad mein unka anusaran karte hain. yeh kaise hota hai? iski anek vyaakhyaaeain ki gayi hain. unamein se adhik sveekrut mat yeh hai ki anek peedhiyon ke prati varsh pravrajan ke kaaran pakshiyon mein anya janmajaat gunon, jaise theek samay par, bina kisi poorv anubhav ke, jaatipranpara ke anusaar ek vishesh prakaar ka need nirmaan karna hai, usi bhaaainti bina kisi poorv anubhav ke pravrajan bhi ek janmajaat gun ho gaya hai.

pakshi sudoor pradeshon ke raaste ka kis prakaar pata lagaate hain

dhruvataara evam uske paas sthit taare pakshiyon ke liye raat mein chumbakeeya sui (kutubanuma) ki tarah kaam karte hain.

pakshi sudoor pradeshon ke raaste ka kis prakaar pata lagaate hain? iske vishay mein bhi anek anumaan hain jinmein se kuchh pruthvi ke chunbakatv ke prati sookshm sanvedanasheelata, sthalachihron ki drushti dvaara pehchaan ityaadi hain. kintu poorvaanubhavavihin kal ki chidiyon mein door gantavya sthaan aur uske path ko nirdhaaran ab bhi rahasyamaya bana hua hai.

achook tatha niyamit punaraagaman

jis prakaar manushya sudoor ki yaatra kar fir apne ghar ko laut aata hai, theek usi bhaaainti pakshi hajaaron kilometer ki yaatra kar aur sharad ritu kisi sudoor sthaan mein vyateet kar na keval apne greeshm-nivaas-kshetr mein hi pahuainch jaate hain, balki apne tyakt ghonsale mein bhi pahuainch jaate hain. chidiyon ko chhalla pahanaane ki vidhi (banding) se yeh sthaapit ho gaya hai ki Europe mein abaabeel praaya: na keval usi basti mein pahuainch jaati hai, balki usi ghar mein jisko chhodkar vah sudoor ki yaatra par gayi thi, pahuainch jaati hai. abaabeelein is yaatra mein 9,677 kilometer ki doori tay karti hain. yaheen baat anya vaastavik pravrajan karanevaali chidiyon mein bhi pai jaati hai.

anek varshon ke nireekshan ke falasvaroop prakaashit kuchh gyaat tathyon se pata chalta hai ki chidiyaaain na keval apne nivaasakshetr aur puraane need mein hi pahuainch jaati hai, balki theek usi din lautakar aa jaati hain jis din ve pichhle varsh mein lautakar I theen. ataev jab itni lambi yaatra karti hon to ek nishchit samay par lautakar pakshiyon ka apne ghonsale mein upasthit ho jaana aur bhi aashcharyajanak hai.

sharad yaatriyon ki vibhinn avasthaaeain

Bhaarat ke vibhinn kshetron mein sharad mein aagaman karanevaale pratyek sharadyaatri pakshi ki sthiti bhinn hoti hai. udaaharan ke liye kisi bhi sthaan ko le lein, jaise madhya Bhaarat ka Bhopal kshetr. pakshiyon ki adhikaansh jaatiyaaain, jo uttar ya uttar pashchim seemaant pradeshon se sharad ritu mein, sudoor dakshin ki ya lanka ki, us desh se hokar yaatra karti hain, ve Bhopal hokar jaati hain. in yaatriyon mein se kuchh to peechhe rah jaate hain aur ve sharad ritu bhar Bhopal mein dekhein ja sakte hain. inka ham vaastavik sharadyaatri ke antargat vargeekaran kar sakte hain, kintu kuchh keval sharad ritu ke aagaman par thode samay ke liye hi rahate hain aur uske baad dikhaai naheen padte kyonki ve vahaaain se aur aage yaatra ke liye prasthaan kar chuke hote hain. ve pun: greeshm ritu ke praarambh mein, jab ve uttar ki taraf lautate hote hain, dikhaai padte hain. ye sharad aur vasant mein pravrajan karanevaale yaatri hote hain. kuchh to sharad ritu mein, jab dakshin ki yaatra par hote hain, tab to dikhaai padte hain, kintu jab ve vasant mein pun: apne nivaas ki or lautate hote hain, tab dikhaai naheen padte, kyonki ve kisi doosare maarg se hokar laut jaate hain. ataev ve pakshi Bhopal mein sharad ritu mein dikhaai padte hain aur vasant mein kisi doosare bhaag mein dikhaai padte hain.

sthaaneeya pravrajan

kuchh chidiyaaain desh ke andar hi ek bhaag se doosare bhaag mein sthaanaparivrtan karti hain, jaise shaah bulabul ya dudhanaju (paradise flycatcher), sunahara polak (golden oriole) aur naurang (pitta). yeh sthaaneeya pravrajan desh ke uttari bhaag ya pahaadon ki talahati mein adhik hota hai, jahaaain bhoomadhyarekha ki apeksha rituparivrtan atyadhik prabhaavakaari hota hai. vaastavik pravrajan karanevaali chidiyon ki bhaaainti inmein bhi pravrajan kramik aur niyamit hota hai. desh ke kisi bhaag mein koi jaati greeshm ritu mein, koi jaati barasaat mein aur koi jaati sharad mein aagaman karti hai. iske atirikt ek anya prakaar ka bhi sthaanaparivrtan baraabar hota rahata hai, jo aahaar par prabhaav daalanevaali sthaaneeya paristhitiyon, jaise garmi, sookha ya baadh ityaadi, athva kisi vishesh prakaar ke fool lagne aur fal pakane ki ritu, ke kaaran hota hai. us samay chidiyaaain ek kshetr se doosare kshetr mein chali jaati hain.

asaadhaaran sthaaneeya pravrajan

kabhi-kabhi asaadhaaran paristhitiyon se baadhya hokar apne upayukt nivaasasthaan ki chhodkar bhojan ki talaash mein chidiyaaain kisi anya kshetron mein bhi bhraman karti hui pai jaati hain. ataev kisi kshetr mein kisi bhi samay mein pakshiyon ki janasankhya sthaayi naheen rahati, kyonki sabhi kshetron mein pakshiyon ka aagaman aur niryaman sarvada hota rahata hai.

ooainchaai sambandhi pravrajan (Altitudinal Migration)

himaalaya ke ooainche pahaadon mein rahanevaali chidiyaaain jaade mein neeche utar aati hai aur is prakaar toofaani mausam aur himrekha se neeche chali aati hai. vasant ke aagaman par jab baraf galane lagti hai aur himrekha oopar ki or badh jaati hai, tab ve ande dene ke liye pahaadon ke oopari bhaag mein pun: chadh jaati hain. yeh kram keval ooainchaai mein rahanevaale pakshiyon mein hi naheen varan neeche rahanevaali chidiyon mein bhi chalta rahata hai.

chidiyon ke pravrajan ka vaigyaanik gyaan praapt karne ke atirikt prakaar ke avalokanon ke liye bhi Britain tatha amareeka mein bahusankhyak chidiyon ke pair mein ailyoominiym ki halki aur ankit angoothiyaan pahana di jaati hai. yeh vidhi amareeka mein pakshivlayan (birdringing) athva pakshiptabandhan (bird banding) kahalaati hai. ismein kramasankhya ke atirikt sthaan ka pata bhi ankit rahata hai. chidiyon ko aaingoothi pahanaakar unka poorn vivran ek pustika mein likh kar unhein chhod diya jaata hai. ab in chidiyon ke sudoor sthaanon pahuainchane par inhein maarkar athva fainsaakar inki angoothi utaar li jaati hai aur ye jis sthaan se udi theen, us pate par bhej di jaati hai. jab kaafi sankhya mein is prakaar ki taalika ikatthi ho jaati hai tab in taalikaaon ka vishleshan karke uske aadhaar par kisi vishesh jaati ki chidiya ke pravrajan ke maarg athva anya kisi samasya ka hal nirdhaarit kiya jaata hai. ataev pashchimi Germany aur poorvi prasha mein shvet bak ke balayan ke falasvaroop yeh nishchit aur ni:sandigdh roop se sthaapit ho chuka hai ki poorvi Asia ki chidiyaaain dakshin-poorvi maarg se baalakan hoti hui Africa ka bhraman karti hai, jabki pashchim Germany ke shvet bak dakshin pashchimi maarg se Spain hokar Africa jaate hain. Bikaner mein isi prakaar ki aaingootheedhaari chidiyon ke praapt hone se hamein pata chala hai ki kuchh shvet bak jo hamaare desh mein, sharad ritu mein, aate hain, ve Germany ke hote hain. Bhaarat mein is prakaar ka pakshivlayan ka kaarya bahut thoda hua hai. kintu jitna kuchh hua hai usase praapt soochanaaeain bahut hi mahatvapoorn aur upayogi siddh hui hain.

pravrajan ke samay udaan ki ooainchaai aur gati

pravrajan karanevaali chidiyon ki gati vibhinn chidiyon mein vibhinn hoti hai aur yeh gati kai baaton, jaise vaayu ki disha, mausam ityaadi par nirbhar karti hai. batakhon aur hanson mein udaan ki gati (cruising speed) 64 se 80 kimi. prati ghante pai gayi hai aur anukool mausam mein yeh gati 90 se 97 kimi. ya isse adhik pai gayi hai. din raat nirantar udkar yaatra karanevaali chidiyon mein yeh gati 9.5 se 17.7 kimi. prati ghanta hoti hai. nimnalikhit saarani se yeh anumaan kiya ja sakta hai ki ek baar ki udaan (hop) mein kaun chidiya kitni doori tay karti hai :

pakshi ka naam doori (kilometer) samay (ghante)
kaarandavakukkut (coot) 258.080 6
raajabak (stork) 251.625 6
teetar (woodcock) 403.250-483.9 11
tittibh (plover) 887.150 11

poorvi sunahara tittibh (eastern golden plover ya Caradrius dominicus fulvus) bina kaheen ruke lagaataar udkar 3226.00 kimi. ke khule samudra ko paar kar jaata hai. yeh tittibh sharad ritu mein, Bhaarat mein bhraman karne aate hain. yeh pashchimi alaaska aur uttar-poorv saaibiriya mein ande deta hai aur havaai dveepon ka niyamit roop se bhraman karta hai. chaaha (Copella hardwickii) jiski maada keval Japan mein ande deti hai, jaada poorvi Australia aur taijamaaniya mein vyateet karta hai, is prakaar avashya hi 4839.00 kimi. ki doori bina kahi ruke nirantar udkar paar kar jaata hai. kuchh aur bhi aisi chidiyaaain hai, jo bina daana paani ke bahut badi doori paar jaati hain. adhik door ki yaatra karanevaali bhaarateeya chidiyon mein sambhavat: mein bhandu teetar (wood cock, Scolopax rusticola) hai jiska ande dene ka sabse niktavarti sthaan himaalaya mein hain. kuchh jhandu teetar jaada neelagiri athva dakshin ki anya pahaadiyon mein bitaate hain aur uske beech anya kaheen naheen milte. isse itna spasht hai ki ye ek udaan mein kam se kam 2419.5 kimi. ki doori avashya hi paar karte hain.

pehle aisa vishvaas kiya jaata tha ki pravrajan karanevaali chidiyaaain bahut ooainchaai par udti hain, kyonki isse unako, sthaan ka nirdhaaran karne, hava ke dvaara utpann avarodh kam hone, ityaadi ka laabh hota hai. kintu ab yeh paaya gaya hai ki yadi kisi ooainchi parvatamaala ko paar karna naheen hua to vastut: ye pravrajan karanevaali chidiyaaain 396.24 meter ki ooainchaai par udti hain aur birli hi chidiya 914.4 meter ki ooainchaai tak ki jaati hai. jab samudra paar karna hota hai athva yahaaain kisi prakaar ke vruksh ya pahaad ka avarodh naheen hota, tab kuchh chidyaaain svabhaavat: isse bhi kam ooainchaai par udti hain. haaain, yadi aavashyakta hui to chidiyaaain bahut ki adhik ooainchaai se bhi ud sakti hain. 3.048 meter se lekar 8229.6000 meter tak ki ooainchaai par udne ka ullekh paaya jaata hai.

inhein bhi dekhein

baahari kadiyaaain