Question

    Migration(迁徙), is a long journey carried out by some birds to other areas where they hope to find more food and a warmer place to spend winter. Hundreds or thousands of miles' journey is actually difficult and dangerous. So why do birds migrate?1.However, it all comes down to survival.

Migrating for a Meal

For all birds, one of the main driving forces behind migration is food shortage. If all birds were to stay in the same warm regions all the year round, food would become lacking and producing their young would be less successful. As food resources are rich in the north each spring, millions of birds migrate there for the food supplies.2.

Migrating for Family

Over thousands of years, birds have evolved different migration patterns, timing and destinations to fly around the world to produce their young. Birds take advantage of a wide variety of suitable conditions to raise their young.3.

Migrating for Climate

Birds have evolved different types of feathers to survive different climates.4.So many birds leave the Arctic producing grounds, for example, when temperatures begin to fall and they need warmer habitats. Similarly, the hottest regions can be a bad environment for raising little chicks, and they will choose cooler areas to lay eggs.

Migrating for Predators(掠食动物)

Habitats that have rich food resources all the year round also attract a greater number of predators that can threaten their nests.5.It gives their young a better chance of reaching maturity. Many birds even migrate to specialized habitats that are nearly inaccessible to predators.

A.Birds always tend to fly to warmer places.

B.And changes in those climates can affect migration.

C.This increases the surviving chances of little chicks.

D.Birds have adapted themselves to their own surroundings.

E.There is more than one reasons for different birds to migrate

F.As the food supplies decrease in fall, they return to warm regions.

G.So birds migrate to different habitats to avoid being eaten by predators.

Answer

1.E

2.F

3.C

4.B

5.G

【解析】

这是一篇说明文。文章介绍鸟类的迁徙的原因。

1.根据上文提示“那么为什么鸟类会迁徙呢?”承接上文，E项There is more than one reasons for different birds to migrate（不同鸟类迁徙的原因不止一个）切题。故选E。

2.根据上文提示“由于北方的食物资源丰富，每年春天都有数以百万计的鸟迁徙到那里寻找食物”。承接上文，F项As the food supplies decrease in fall, they return to warm regions.（随着秋天食物供应的减少，它们回到温暖的地区。）切题。故选F。

3.根据上文提示“鸟类利用各种各样的适宜条件来养育后代。”承接上文，C项This increases the surviving chances of little chicks.（这增加了小企鹅的生存机会。）切题。故选C。

4.根据上文提示“鸟类进化出不同类型的羽毛以适应不同的气候。”再根据下文提示“例如，当气温开始下降，需要更温暖的栖息地时，许多鸟类离开北极的产地。”承接上下文，B项And changes in those climates can affect migration.（这些气候的变化会影响迁徙。）切题。故选B。

5.根据上文提示“全年都有丰富食物资源的栖息地也吸引了大量的捕食者，这些捕食者会威胁到它们的巢”。再根据下文提示“这使它们的后代有更好的机会成熟。”承接上下文，G项So birds migrate to different habitats to avoid being eaten by predators.（所以鸟类迁徙到不同的栖息地以避免被捕食者吃掉。）切题。故选G。