劍橋雅思11Test3Passage2閱讀原文翻譯Great Migrations

劍橋雅思11Test3Passage2閱讀原文翻譯Great Migrations，今天中國教育在線就來為大家分析這個(gè)問題。

Great Migrations

偉大的遷徙

劍橋雅思11 Test3 Passage2閱讀原文翻譯

第1段

Animal migration,however it is defined,is far more than just the movement of animals.It can loosely be described as travel that takes place at regular intervals–often in an annual cycle–that may involve many members of a species,and is rewarded only after a long journey.It suggests inherited instinct.The biologist Hugh Dingle has identified five characteristics that apply,in varying degrees and combinations,to all migrations.They are prolonged movements that carry animals outside familiar habitats;they tend to be linear,not zigzaggy;they involve special behaviours concerning preparation(such as overfeeding)and arrival;they demand special allocations of energy.And one more:migrating animals maintain an intense attentiveness to the greater mission,which keeps them undistracted by temptations and undeterred by challenges that would turn other animals aside.

無論如何定義動物遷徙，它都不僅僅是動物的移動而已。它可以大致被描述為按照規(guī)律的間隔（通常以一年為周期）所進(jìn)行的旅行。這通常涉及某一種群中的大部分成員，并且只有在漫長的旅程之后才能得到獎勵。這種行為顯示出它們的遺傳本能。生物學(xué)家Hugh Dingle總結(jié)出5個(gè)在不同程度上或者按照不同組合適用于所有遷徙的特點(diǎn)。它們是漫長的移動，將動物帶出熟悉的棲息地；它們通常是線性的，而非蜿蜒曲折的；它們涉及到與準(zhǔn)備（如過量飲食）和到達(dá)相關(guān)的特殊行為；它們需要獨(dú)特的能量分配。此外還有一點(diǎn)，遷徙中的動物對這一偉大的任務(wù)高度專注。這讓它們不會被誘惑所干擾，面對讓其他動物止步不前的挑戰(zhàn)不屈不撓。

第2段

An arctic tern,on its 20,000 km flight from the extreme south of South America to the Arctic circle,will take no notice of a nice smelly herring offered from a bird-watcher’s boat along the way.While local gulls will dive voraciously for such handouts,the tern flies on.Why?The arctic tern resists distraction because it is driven at that moment by an instinctive sense of something we humans find admirable:larger purpose.In other words,it is determined to reach its destination.The bird senses that it can eat,rest and mate later.Right now it is totally focused on the journey;its undivided intent is arrival.Reaching some gravelly coastline in the Arctic,upon which other arctic terns have converged,will serve its larger purpose as shaped by evolution:finding a place,a time,and a set of circumstances in which it can successfully hatch and rear offspring.

一只北極燕鷗在它從南美最南端到北極圈長達(dá)20000公里的飛行中，不會注意到路途上鳥類觀察者的小船所提供的美味鯡魚。盡管當(dāng)?shù)睾ｚt文章來自 雅思會為這些饋贈而貪婪地俯沖下來，燕鷗卻繼續(xù)向前飛行。這是為什么呢？北極燕鷗之所以拒絕這一誘惑是因?yàn)槟菚r(shí)它被一種我們?nèi)祟愂謿J佩的本能所驅(qū)動著，即更大的目標(biāo)。換句話說，它下定決心要到達(dá)自己的目的地。這只鳥感覺自己可以稍后進(jìn)食、休息和交配。現(xiàn)在，它全神貫注于這一旅程，全部的心思都是抵達(dá)。到達(dá)北極沙礫遍布、其他北極燕鷗聚集的海岸便能達(dá)成由進(jìn)化所塑造出來的更大的目標(biāo)：找到某個(gè)地方，某個(gè)時(shí)間，以及一系列的環(huán)境條件。在其中，它可以成功地孵化和養(yǎng)育后代。

第3段

But migration is a complex issue,and biologists define it differently,depending in part on what sorts of animals they study.Joel Berger,of the University of Montana,who works on the American pronghorn and other large terrestrial mammals,prefers what he calls a simple,practical definition suited to his beasts:‘movements from a seasonal home area away to another home area and back again’.Generally the reason for such seasonal back-and-forth movement is to seek resources that aren’t available within a single area year-round.

但是，遷徙是一個(gè)復(fù)雜的問題，根據(jù)生物學(xué)家所研究的動物種類不同，他們對它的定義也各有不同。蒙大拿大學(xué)、研究美國叉角羚和其他大型陸生哺乳動物的Joel Berger，傾向于使用一個(gè)適用于他所研究的動物類型的，簡單實(shí)用的定義：“從一個(gè)季節(jié)性的棲息地離開，到另外一個(gè)棲息地去，并再次返回的過程”。大體來說，這種季節(jié)性往返移動的原因是為了尋找在某個(gè)單一區(qū)域并非全年存在的資源。

第4段

But daily vertical movements by zooplankton in the ocean–upward by night to seek food,downward by day to escape predators–can also be considered migration.So can the movement of aphids when,having depleted the young leaves on one food plant,their offspring then fly onward to a different host plant,with no one aphid ever returning to where it started.

但是，海洋中浮游生物每天的垂直移動-夜里向上尋找食物，白天向下躲避捕食者-也可以被認(rèn)為是遷徙。蚜蟲的活動同樣如此，在吃光了一株植物上的嫩葉之后，它們的后代會飛到一株不同的宿主植物上。沒有一個(gè)蚜蟲會返回到出發(fā)的地方。

第5段

Dingle is an evolutionary biologist who studies insects.His definition is more intricate than Berger’s,citing those five features that distinguish migration from other forms of movement.They allow for the fact that,for example,aphids will become sensitive to blue light(from the sky)when it’s time for takeoff on their big journey,and sensitive to yellow light(reflected from tender young leaves)when it’s appropriate to land.Birds will fatten themselves with heavy feeding in advance of a long migrational flight.The value of his definition,Dingle argues,is that it focuses attention on what the phenomenon of wildebeest migration shares with the phenomenon of the aphids,and therefore helps guide researchers towards understanding how evolution has produced them all.

Dingle是一名研究昆蟲的進(jìn)化生物學(xué)家。他的定義與Berger相比要更加精致一些，列舉出遷徙區(qū)別于其他形式移動的5個(gè)特征。它們考慮到以下事實(shí)：例如蚜蟲在開啟自己宏大旅程的時(shí)候會變得對來自天空的藍(lán)色光線更為敏感，而在適合降落的時(shí)候會對反射自嫩葉的黃色光線更為敏感。鳥類會在漫長遷徙飛行之前會大量飲食來讓自身變得肥胖。Dingle認(rèn)為，其定義的價(jià)值在于，它將注意力放在角馬遷徙與蚜蟲遷徙現(xiàn)象的共性上，并由此來幫助引導(dǎo)研究者理解進(jìn)化是如何產(chǎn)生所有這些共性的。

第6段

Human behaviour,however,is having a detrimental impact on animal migration.The pronghorn,which resembles an antelope,though they are unrelated,is the fastest land mammal of the New World.One population,which spends the summer in the mountainous Grand Teton National Park of the western USA,follows a narrow route from its summer range in the mountains,across a river,and down onto the plains.Here they wait out the frozen months,feeding mainly on sagebrush blown clear of snow.These pronghorn are notable for the invariance of their migration route and the severity of its constriction at three bottlenecks.If they can’t pass through each of the three during their spring migration,they can’t reach their bounty of summer grazing;if they can’t pass through again in autumn,escaping south onto those windblown plains,they are likely to die trying to overwinter in the deep snow.Pronghorn,dependent on distance vision and speed to keep safe from predators,traverse high,open shoulders of land,where they can see and run.At one of the bottlenecks,forested hills rise to form a V,leaving a corridor of open ground only about 150 metres wide,filled with private homes.Increasing development is leading toward a crisis for the pronghorn,threatening to choke off their passageway.

然而，人類行為對動物遷徙有著負(fù)面影響。叉角羚雖然與羚羊無關(guān)，但看起來很像。它是新世界速度最快的陸生哺乳動物。其中一個(gè)族群會在美國西部大提頓國家公園的山脈之間度過夏天，然后從其山間的夏季牧場沿一條狹窄的路徑南下，穿過河流，到達(dá)平原。在這里，他們等待寒冷月份結(jié)束，主要以被風(fēng)吹過露出雪面的灌木為生。這些叉羚羊之所以引人注目是因?yàn)槠溥w徙路線的不變性，以及三個(gè)瓶頸的嚴(yán)重限制。如果它們在春季遷徙中無法通過三個(gè)中的任何一個(gè)，它們就不能到達(dá)食物充足的夏季草場。如果他們在秋季時(shí)不能再次通過，就無法向南逃到被風(fēng)吹拂的平原上，并很有可能在試圖度過厚厚冰雪的冬季中死亡。叉羚羊依賴其遠(yuǎn)視能力和速度來躲避捕食者。他們穿行于陸地高聳開闊的地帶，便于四處觀察和奔跑。在其中一個(gè)瓶頸中，遍布森林的山峰聳立，形成V字形狀，只留下一條大約150米寬的走廊。其間充滿私人住宅。不斷的發(fā)展正在引發(fā)一場叉羚羊的生存危機(jī)，有堵塞它們通道的風(fēng)險(xiǎn)。

第7段

Conservation scientists,along with some biologists and land managers within the USA’s National Park Service and other agencies,are now working to preserve migrational behaviours,not just species and habitats.A National Forest has recognised the path of the pronghorn,much of which passes across its land,as a protected migration corridor.But neither the Forest Service nor the Park Service can control what happens on private land at a bottleneck.And with certain other migrating species,the challenge is complicated further–by vastly greater distances traversed,more jurisdictions,more borders,more dangers along the way.We will require wisdom and resoluteness to ensure that migrating species can continue their journeying a while longer.

物種保護(hù)科學(xué)家，以及來自美國國家公園管理局和其他機(jī)構(gòu)的一些生物學(xué)家和土地管理者，現(xiàn)在正努力保護(hù)動物的遷徙行為，而不僅僅是它們的種群和棲息地。一片國家森林將叉角羚的遷徙路線（很大一部分路徑要穿行其中）列為受保護(hù)的遷徙走廊。但無論是森林服務(wù)局還是公園服務(wù)局都無法控制瓶頸地帶私人土地上所發(fā)生的事情。對于其他一些遷徙物種來說，挑戰(zhàn)要更加復(fù)雜一些。它們一路上穿越更長的距離，更多的管轄區(qū)，更多的邊境，面對更多的危險(xiǎn)。我們需要智慧和決心來確保遷徙中的物種能夠?qū)⑺麄兊穆猛具M(jìn)行的更長久一些。

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