Question

    For parents with grown children, sometimes the pain of an empty nest can be better than the pain of a full basement. It turns out birds face a similar but slightly more deadly dilemma. When young birds leave the nest early, they help their future generations survive better but they themselves are more likely to die, according to a new study.

Young birds can have a tough life—as can their parents. A noisy nest attracts predators that can wipe out the entire year's reproductive efforts at one stroke. Thus, bird parents push their young to leave the nest early—even when they are not quite ready—to increase the chances that at least one will survive, making sure all their "eggs" are not in one basket. But these early birds suffer as a result. Their death rate can be as high as 70%, compared with just 12% for species that are late bloomers.

Suspecting survival rates had something to do with how ready the birds were to take wing. An ecologist, Thomas Martin, tested fledgling(雏鸟) flying ability at different ages in about a dozen species and recorded the results with high-speed video.

As expected, younger birds had poorly developed wings and flew badly. Moreover, when researchers forced a gray sparrow called a junco(which has some of the lowest fledgling survival rates among the species studied) to stay in the nest for 13 days instead of 10, more lived to adulthood. Just 10% died within 7 days, compared with 30% for the early birds.

But it turns out that some bird moms are willing to keep their kids in the nest a bit longer. Birds such as the white-breasted nuthatch(五子雀), which nests in well-protected tree holes, let the young hang about longer at home, Martin's team discovered. In contrast, birds that nest on the ground or in the open pushed for early departures. That's because they suffer comparatively high losses of chicks in the nest.

Are there any lessons for human parents? “Some parallels exist,” Martin says, “but with people, there's so much more culture that comes into it.”

1.What does the new study find?

A.Young Birds' early leaving from the nest benefits bird parents themselves.

B.Parents with grown children suffer the pain of an empty nest.

C.There is a strong bond between empty-nest parents and young birds.

D.The wrong time of young birds' leaving may bring the whole family a disaster.

2.Which does the underlined word “predators” in paragraph 2 refer to?

A.The birds' parents. B.The birds' natural enemies.

C.The younger competitors. D.The future generations.

3.What did the case of the gray sparrow show?

A.More birds have poorly developed wings than ever.

B.More gray sparrows live to adulthood than ever.

C.The longer the young stayed in the nests, the higher their survival rates were.

D.The earlier the young left the nests, the higher their survival rates were.

4.What may decide young birds' leaving time from home according to the research?

A.The bird moms. B.The bird species.

C.The wings' shape. D.The location of their nests.

Answer

1.D

2.B

3.C

4.D

【解析】

这是一篇说明文。一项最新研究表明，当幼鸟提早离开巢穴时，它们会帮助后代更好地生存，但它们自己更有可能死亡。文章说明了这一现象产生的原因，以及科学家对此的研究过程。

1.

细节理解题。根据第二段中A noisy nest attracts predators that can wipe out the entire year's reproductive efforts at one stroke. Thus, bird parents push their young to leave the nest early—even when they are not quite ready—to increase the chances that at least one will survive, making sure all their "eggs" are not in one basket.可知聒噪的鸟巢会吸引捕食者，它们会一举消灭一整年的繁殖努力。因此，鸟类父母会敦促它们的幼鸟尽早离开鸟巢——即使它们还没有完全准备好——以增加至少有一只会存活下来的机会，确保它们的“蛋”不都在一个篮子里。由此可知，新的研究发现幼鸟离开的时间不对，可能会给全家带来灾难。故选D。

2.

词义猜测题。根据后文that can wipe out the entire year's reproductive efforts at one stroke可知聒噪的鸟巢会吸引鸟类的天敌，这些天敌会一举消灭鸟类一整年的繁殖努力。由此可知，划线单词指的是“鸟类的天敌”。故选B。

3.

推理判断题。根据第四段中Moreover, when researchers forced a gray sparrow called a junco(which has some of the lowest fledgling survival rates among the species studied) to stay in the nest for 13 days instead of 10, more lived to adulthood. Just 10% died within 7 days, compared with 30% for the early birds.可知此外，当研究人员强迫一只名为灰麻雀的灰麻雀（在研究物种中有一些最低的羽翼成活率）在鸟巢中停留13天而不是10天时，更多的活到成年期。只有10%的麻雀在7天内死亡，而在早期死亡的比例为30%。由此可推知，灰麻雀的情况说明了幼鸟在巢中停留的时间越长，它们的存活率就越高。故选C。

4.

细节理解题。根据第五段中In contrast, birds that nest on the ground or in the open pushed for early departures. That's because they suffer comparatively high losses of chicks in the nest.可知相比之下，在地面或露天筑巢的鸟类则要求提早出发。这是因为它们在巢中损失的雏鸟相对较多。由此可知，根据这项研究，是巢穴的位置决定了雏鸟离开家的时间。故选D。