A
As the climate warms, birds are shrinking (缩小) and their wingspans are growing, according to a new study.Researchers analyzed 70,716 birds from 52 kinds of North American migratory (迁徙的) bird species collected over 40 years.The authors say the study is the largest of its kind and that the findings are important to understanding how animals will adapt to climate change.
“We found almost all of the species were getting smaller.” said lead author Brian Weeks, an assistant professor at the University of Michigan.“The species were pretty diverse, but responding in a similar way，” he said.“The consistency (一致性) was shocking.” He said studies of animal responses to climate change often focus on shifts in geographical range or timing of life events, like migration and birth.But this study suggests body morphology (形态) is a crucial third aspect.
“That's one major implication，” he said, “It's hard to understand how birds will adapt without taking all three of these things into consideration.”
The findings showed that from 1978 to 2016, the length of the birds' lower leg bone shortened by 2.4%.Over the same time, the wings lengthened by 1.3%.
The evidence suggests warming temperatures caused the decrease in body size, which in turn caused the increase in wing length.
“Migration is an incredibly taxing thing they do，” Mr Weeks said, explaining that the smaller body size means less energy available for the birds to complete their long journeys.He says the birds most likely to survive migration were the ones with longer wingspans and smaller bodies.
The scientists aren't exactly sure why warmer temperatures cause birds to shrink.One theory is that smaller animals are better at cooling off, losing body heat more quickly.
语篇解读：本文是一篇说明文。研究表明，随着气候变暖，鸟类数量在减少，鸟的体型在缩小，翅膀在增长，原因未知。
1．What made Brian Weeks feel astonished?
A．It took 40 years to collect 70,716 birds from North America.
B．Many birds are shrinking when responding to the climate change.
C．All migratory bird species were collected to do the important research.
D．So many researchers take part in the largest study to work out the findings.
解析：选B 细节理解题。根据第二段Brian Weeks所说内容可知，Brian Weeks认为许多鸟类在应对气候变化时都在缩小是令人震惊的，故选B项。
2．What does the underlined word “taxing” most probably mean?
A．Tiring. B．Important.
C．Easy. D．Pleasant.
解析：选A 词义猜测题。根据画线词所在句后Mr Weeks said, explaining that the smaller body size means less energy available for the birds to complete their long journeys.可知，迁徙是一件非常耗费能量的事情，故画线词所在的句子意思是：迁徙是一件非常疲劳的事情。故画线词义为“疲劳的”，故选A项。
3．What can we infer from the last paragraph?
A．The migratory birds aren't big.
B．The temperatures will be higher.
C．The scientists will go on further study.
D．The smaller animals will surely live longer.
解析：选C 推理判断题。根据最后一段中The scientists aren't exactly sure why warmer temperatures cause birds to shrink.可知，科学家还不知道气温升高导致鸟类缩小的原因。因此，科学家们将继续深入研究，故选C项。
4．What's the best title for the text?
A．All of the Birds Are Getting Smaller
B．Animals Are Adapting to Climate Change
C．Climate Change Is Causing Birds to Shrink
D．Scientists Are Finding Causes of Warm Climate
解析：选C 标题归纳题。通读全文可知，本文主要介绍了随着气候变暖，鸟类数量在减少，鸟的体型在缩小，翅膀在增长，原因未知。因此本文最好的题目是C项(气候变化正导致鸟类缩小)。本题易误选A项(所有的鸟都在变小)，由于本选项未表明造成鸟变小的原因，故A项错误。
