With weather getting warmer,animals have begun to change in response to the new condition.And some of them have become smaller.Some scientists thought this might be an adaptation to a warmer world; smaller bodies should be able to lose heat better.But now a new study has found that for red knot birds,that’s not the case.
Ecologist Jan van Gils and his colleagues have been studying these birds for 33 years.Over the course of their research,van Gils and his team have found that in Russia where the red knots summer,snowmelt and spring have been advancing by half a day per year on average.Over more than thirty years,the researchers caught and measured nearly 2,000 birds.In years when the snowmelt had arrived particularly early,the birds were likely to be smaller and have shorter bills (鸟嘴).
The birds leave the coast of Western Africa,where they winter,and fly north toward Russia.The birds are supposed to arrive in spring,so they can lay their eggs and when their chicks hatch out,there will be a wealth of arthropod (节肢动物) insects to feed their young.
But even though the red knots are advancing their arrival date by about a quarter of a day per year,it is not enough to keep up with the snowmelt.And in years when the snowmelt arrives early,the arthropods reach the greatest quantity before the birds need them.Therefore,chicks miss out on eating well and they grow up to be smaller and have shorter bills.
Being smaller and having a shorter bill isn’t a problem in Russia—but it is in Africa.There,adult birds feed on thin-shelled bivalves (双壳贝类),Loripes lucinalis.But the bivalves are buried deep.However,other options,Dosinia isocardia bivalves and seagrass rhizomes (根茎),which only the youngest birds rely on,are not abundant or nutritious.
Van Gils and his colleagues found that,in their first year,shorter-billed red knots don’t survive as well in Africa.The majority of birds that survive are the long-billed birds.
1.How did Jan van Gils and his colleagues reach the conclusion?
A.By comparing red knots with other birds.
B.By dividing 2,000 red knots into several groups.
C.By watching and examining red knots for three decades.
D.By analyzing studies that have been published in Science.
2.What influence does early snowmelt have on red knots?
A.Their chicks don’t have enough to eat. B.Their eggs take more time to hatch out.
C.They need to find other places for summer. D.They arrive in Russia half a day earlier each year.
3.Why do few adult short-billed red knots survive in Africa?
A.Because they can’t find arthropod insects to eat.
B.Because they can’t access Loripes lucinalis bivalves.
C.Because Dosinia isocardia bivalves they need are rare.
D.Because seagrass rhizomes they feed on are not nutritious.
4.What’s the purpose of the text?
A.To tell a story. B.To provide facts.
C.To make an announcement. D.To put forward suggestions.
语篇解读:本文是说明文。研究表明受到全球变暖的影响,在融雪期特别早的年份孵化出来的红腹滨鹬会体格变小、鸟嘴变短,这直接影响它们的生存。
答案及剖析:
1.C 细节理解题。根据第二段中的Ecologist Jan van Gils and his colleagues have been studying these birds for 33 years.及Over more than thirty years,the researchers caught and measured nearly 2,000 birds.可知,Jan van Gils和他的同事通过追踪研究红腹滨鹬30余年才得出了他们的结论。
2.A 细节理解题。根据第四段中的And in years when the snowmelt arrives early,the arthropods reach the greatest quantity before the birds need them.Therefore,chicks miss out on eating well可知,如果融雪期提前到来的话,等红腹滨鹬的幼鸟孵化出来时,它们已经错过了节肢动物数量最多的时候,因此没有足够的食物吃。
3.B 推理判断题。根据倒数第二段中的adult birds feed on thin-shelled bivalves,Loripes lucinalis.But the bivalves are buried deep可推测,Loripes lucinalis这种贝类在地下比较深的地方,因此嘴短的红腹滨鹬吃不到它们,影响生存。
4.B 写作目的题。通读全文可知,本文介绍了在融雪期特别早的年份孵化出来的红腹滨鹬会体格变小、鸟嘴变短,从而直接影响它们生存的事实。故B项正确。
