2017年4月15日托福阅读真题+题目+答案：Bird Colonies

2017年4月15日托福阅读真题+题目+答案：Bird Colonies

Paragraph 1

About 13 percent of bird species, including most seabirds, nest in colonies. Colonial nesting evolves in response to a combination of two environmental conditions: (1) a shortage of nesting sites that are safe from predators and (2) abundant or unpredictable food that is distant from safe nest sites. First and foremost, individual birds are safer in colonies that are inaccessible to predators, as on small rocky islands. In addition, colonial birds detect predators more quickly than do small groups or pairs and can drive the predators from the vicinityof the nesting area. Because nests at the edges of breeding colonies are more vulnerable to predators than those in the centers, the preference for advantageous central sites promotes dense centralized packing of nests.

1.The word “vicinity” in the passage is closet in meaning to

A. protection

B. region

C. population

D. resources

2.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

A. It is more advantageous for birds to choose central locations for their colonies rather than locations near the edges of their territory.

B. Compared to nests at the edges of colonies, centrally located nests are preferred for their safety from predators and therefore are more densely packed together.

C. Predators generally prefer the densely packed, central portion of nesting colonies, which can make this part of the colony more vulnerable to predators.

D. Birds nesting in colonies that are vulnerable to predators tend to prefer more densely packed nests to those less densely packed.

Paragraph 2

The yellow-rumped cacique, which nests in colonies in Amazonian Peru, demonstrates how colonial birds prevent predation. These tropical blackbirds defend their closed, pouchlike nests against predators in three ways. First, by nesting on islands and near wasp nests, caciques are safe from arboreal mammals such primates. Second, caciques mob predators (work together as a group to attack predators). The effectiveness of mobbing increases with group size, which increases with colony size. Third, caciques hide their nests from predators by mixing active nests with abandoned nests. Overall, nests in cluster on islands and near wasp nests suffer the least predation.

3.Paragraph 2 implies which of the following about yellow-rumped caciques?

A. They are comparatively unlikely to be harmed by the wasps that attack their predators.

B. They are able to protect their nests without using colonies.

C. Mixing active nests with abandoned nests is the least useful way of defending their nests.

D. Most of their predators are members of other bird species.

4. Paragraph 2 claims that yellow-rumped cacique colonies defend themselves from predators in all of the following ways EXCEPT

A. They establish colonies in hard-to-reach places.

B. They physically attack invading predators.

C. They hide active nests among previously used ones.

D. They limit the size of their colonies so they are hard to find.

Paragraph 3

Coordinated social interactions tend to be weak when a colony is first forming, but true colonies provide extra benefits. Synchronized nesting, for example, produces a sudden abundance of eggs and chicks that exceeds the daily needs of local predators. Additionally, colonial neighbors can improve their foraging by watching others. This behavior is especially valuable when the off-site food supplies are restricted or variable in location, as are swarms of aerial insects harvested by swallows. The colonies of American cliff swallows, for example, serve as information centers from which unsuccessful individual birds follow successful neighbors to good feeding sites. Cliff swallows that are unable to find food return to their colony, locate a neighbor that has been successful, and then follow that neighbor to its food source. All birds in the colony are equally likely to follow or to be followed and thus contribute tothe sharing of information that helps to ensure their reproductive success. As a result of their enhanced foraging efficiency, parent swallows in large colonies return with food for their nestlings more often and bring more food each trip than do parents in small colonies.

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2017年4月15日托福阅读真题+题目+答案：Bird ，完整版下载，10元有偿！