题目内容：

    Every year, little black-and-white birds called pied flycatchers(斑姬鹟) travel from sub-Saharan Africa to northern Europe to feast on caterpillars (毛毛虫), claim a nest, and have babies. And they fly back a few months later. But recently, some flycatchers have arrived only to find their nesting sites occupied by great tits (大山雀). And those birds don’t just chase flycatchers away—they attack them, kill them, and eat their brains.

Great tits live in European forests all year round. Flycatchers are regular vacationers. Since the 1980s,  flycatchers’ reproductive season has been inching up earlier in the month of April. Warm spring temperatures have caused caterpillar populations to boom. To adapt to that, flycatchers arrive a bit earlier, too. That won’t be too big a problem. But now, tits delay their breeding period a bit in April, so they overlap with the flycatchers, and violence begins.

Moreover, there’s limited nesting space in many of these birds’ favorite forests—the trees can be quite young and have very few tree holes where birds can nest. Volunteers and academics have placed nestboxes to help. But with climate change, birds’ breeding schedules getting closer, there aren’t enough nestboxes to go around. Unfriendly hosts—the tits, eat their brains.

“Great tits are superior competitors when it comes down to a fight, ” said Jelmer Samplonius, lead author of a study. “People see it as a cute garden bird, but some of them have a real anger management problem. ” Luckily, the murdered birds were often surplus males that arrive late. The deaths haven’t had a big impact on the population because those late males probably won’t have had babies anyway. But there’s always the chance that it could get worse.

“Whatever the flycatcher population’s future may hold, ” Samplonius said, “this is a good example of why it’s essential to study how climate change can shift animals’ schedules, often with deadly consequences. Understanding different responses to changing environments will be an important part of species assessments in coming years.”

1.What has happened to pied flycatchers recently?

A.They couldn’t get enough food.

B.Their nesting sites were destroyed.

C.Their babies have become less likely to survive.

D.Their lives have been threatened by another kind of birds.

2.Which is one of the causes of the violence between pied flycatchers and great tits?

A.The change in migration of flycatchers. B.The delay of flycatchers’ reproductive season,

C.The reduction of both birds’ favorite forests. D.The two birds’ sharing the same food.

3.Which can best describe great tits?

A.Ugly. B.Smart. C.Aggressive. D.Lazy.

4.What can be the best title for the text?

A.A terrible bird murder B.Birds’ struggle to hunt

C.Birds’ influence on climate change D.The future of mixed species communities