Barred owls(大林鸮猫头鹰) are a large species native to eastern North America, but they began moving west at the start of the 20th century. By 1973, large numbers of barred owls had arrived in the western state of Washington. Later they moved south into Oregon and California.

In parts of the Pacific Northwest, the owls are now believed to be causing a drop in the population of a smaller, less aggressive bird: the northern spotted owl. In many ways, the barred owl is the spotted owl's worst enemy. The barred owl has more babies per year and eats the same animals, like squirrels and wood rats. And their numbers are now larger in many parts of the spotted owl's traditional territory.

David Wiens is a biologist with the U.S. Geological Survey, a federal agency that studies the Earth and its natural resources. He and other officials are doing something unusual to protect spotted owls: killing barred owls. It is a controversial, experimental program. More than 2,400 barred owls have already been shot.

Wiens is the son of a well-known bird expert and grew up with the fascination for birds. He has mixed feelings about the program. "It's a little distasteful, I think, to go out killing barred owls to save another owl species," he says. But he adds, “We knew that barred owls were out competing spotted owls and their numbers were growing too fast."

To catch barred owls, officials put digital bird callers on the ground. Then they step back and wait as several sounds from the devices fill the air. All of this happens in the dark of night. Barred owls dislike other birds in their territory, so they will fly down and chase other owls out. That is when Wiens and his team try to shoot them.

【小题1】What's the main problem with spotted owls?

A．They are being starved to death.	B．They have more babies each year.
C．They are invaded by another bird.	D．They are hunted by man.

【小题2】Why are barred owls being killed?

A．They are eating the spotted owls.	B．They are killing each other to survive.
C．They are putting the spotted owls in danger.	D．They are destroying large areas of forests.

【小题3】Why did the officials release the bird sounds?

A．To kill barred owls.	B．To puzzle barred owls.
C．To protect barred owls.	D．To frighten barred owls.

【小题4】What can be the best title for the text?

A．Killing One Animal to Save Another.	B．Keeping the Balance of Nature.
C．Protecting Birds in Danger.	D．Preventing Birds from Playing Fair.