Question

    When fisheries biologist James Drymon noticed feathers in the vomit of a tiger shark, he first assumed they belonged to some unfortunate seabird: a gull, perhaps, or a pelican. But when he and his team genetically sequenced the feathers, the results surprised them: the feathers came from a land-based songbird called a brown thrasher. So what was it doing in a tiger shark’s stomach in the Gulf of Mexico?

Drymon, a researcher at Mississippi State University’s Coastal Research and Extension Center, and his colleagues sorted songbird from a tiger shark’s stomach through the stomach contents of 105 juvenile tiger sharks between 2010 and 2018. Nearly 40 percent had recently feasted on birds that come from dry land. In all, the scientists counted 11 terrestrial bird species showing up on the sharks’ menu. The results were published online in May in Ecology. Researchers have known since the 1960 s that sharks sometimes eat songbirds. “But what was interesting to us was the prevalence of the behavior,” Drymon says, “This is something that happens every year in a high number of sharks.”

Every fall and spring, songbirds undertake dramatic migrations across the Gulf of Mexico. If bad weather comes along, they can be forced to land on the water—which is effectively a death sentence. “The estimate for the number of migrants that die because of storm-related events is in the billions,” Drymon says. He suspects that sharks have long taken advantage of this twice-yearly nutritional bounty raining down from the skies, but scientists have only recently had the genetic tools to confirm this by identifying partially digested feathers.

“The results stressed how interconnected marine and terrestrial ecosystems can be,” says University of Miami marine ecologist Neil Hammerschlag, who was not involved in the study, “It shows how opportunistic these sharks are.”

1.How did James Drymon and his colleagues identify the feathers?

A.By making comparison. B.By checking their DNA.

C.By observing them closely. D.By analyzing previous data.

2.What do we know about tiger sharks?

A.They dislike terrible weather. B.Most of them feed on land birds.

C.They actively catch songbirds for food. D.They are good at making use of opportunities.

3.According to the passage, what do songbirds fear most when they migrate?

A.Sharks in the sea. B.Other larger birds.

C.The stormy weather. D.The long distance.

4.What is the text mainly about?

A.Tiger sharks’ eating habit. B.Researchers’ identification of feathers.

C.Land birds’ suffering a lot when migrating. D.Land birds’ being on the menu of tiger sharks.

Answer

1.B

2.D

3.C

4.D

【解析】

这是一篇说明文。渔业生物学家James Drymon从虎鲨呕吐物中发现了陆地鸣禽的羽翼，从而证实了鲨鱼会利用每年鸟类迁徙的机会来捕食这些陆地鸣禽。文章还介绍了他们研究的经过。

1.

细节理解题。根据第一段中But when he and his team genetically sequenced the feathers, the results surprised them: the feathers came from a land-based songbird called a brown thrasher.可知但当他和他的团队对羽毛进行基因排序时，结果让他们大吃一惊：羽毛来自一种陆地鸣禽——棕色长尾莺。由此可知，James Drymon和他的同事通过检查他们的DNA来识别这些羽毛。故选B。

2.

细节理解题。根据倒数第二段中He suspects that sharks have long taken advantage of this twice-yearly nutritional bounty raining down from the skies, but scientists have only recently had the genetic tools to confirm this by identifying partially digested feathers.可知他怀疑，鲨鱼早就利用了这种每年两次从天空中降下的营养恩惠，但科学家们最近才有了基因工具，通过识别部分消化的羽毛来证实这一点。以及最后一段中It shows how opportunistic these sharks are.可知这说明这些鲨鱼是多么会利用机会。由此可知，虎鲨善于利用机会。故选D。

3.

细节理解题。根据倒数第二段中If bad weather comes along, they can be forced to land on the water—which is effectively a death sentence. “The estimate for the number of migrants that die because of storm-related events is in the billions,” Drymon says.可知如果天气不好，它们就会被迫上岸——这实际上就是死刑。“因风暴相关事件而死亡的迁徙鸟类数量估计有数十亿，”Drymon说。由此可知，鸣禽在迁徙时最害怕暴风雨天气。故选C。

4.

主旨大意题。根据第一段中But when he and his team genetically sequenced the feathers, the results surprised them: the feathers came from a land-based songbird called a brown thrasher. So what was it doing in a tiger shark’s stomach in the Gulf of Mexico?可知但当他和他的团队对羽毛进行基因排序时，结果让他们大吃一惊：羽毛来自一种陆地鸣禽——棕色长尾莺。那么它在墨西哥湾的虎鲨肚子里做什么呢？结合文章主要说明了渔业生物学家James Drymon从虎鲨呕吐物中发现了陆地鸣禽的羽翼，从而证实了鲨鱼会利用每年鸟类迁徙的机会来捕食这些陆地鸣禽。文章还介绍了他们研究的经过。由此可知，文章主要是关于在虎鲨的菜单上有陆地鸟。故选D。