First,the spotted owl was threatened by logging in the Pacific N

First,the spotted owl was threatened by logging in the Pacific Northwest．Now it's in danger from a new enemy,the barred owl．Barred owls have been moving to the Northwest from the eastern part of the United States．Stan Sovern has studied spotted owls．Now when he calls for spotted owls,barred owls are starting to appear．Sovern threw a mouse on the ground,and a barred owl grabbed it. Scientists have learned that spotted owls start to vanish when barred owls come．Some barred and spotted owls have mated and produced hybrid babies．One spotted owl was killed by a barred owl. Professor Ned K．Brown of the University of California-Berkeley says,"In some areas of Washington,the barred owls moved into very dense,deep woods．The same kind of woods that arc opened up,or destroyed by logging,that adversely influences the spotted owls." Ten years have passed since the federal government began protecting the spotted owl．Loggers were forced to limit logging on seven million acres of government land．No one is sure how the arrival of the barred owls will impact laws that protect spotted laws．The barred owls like to live in the deep forests where loggers like to cut down trees．The barred owls will likely keep migrating to the Northwest. When Stan Sovern calls the spotted owl,__.
A、a mouse appears
B、the spotted owl ignores him
C、no one answers
D、barred owls appear
【正确答案】：D
【题目解析】：在这段描述中，文章主要讨论了两种猫头鹰：斑点猫头鹰（spotted owl）和横斑猫头鹰（barred owl）。文章提到，由于伐木活动，斑点猫头鹰在太平洋西北地区受到威胁。但现在，斑点猫头鹰面临着来自横斑猫头鹰的新威胁。横斑猫头鹰从美国东部迁移到西北地区，对斑点猫头鹰的栖息地构成影响。 文章通过Stan Sovern的研究进一步说明了这一点。当Sovern呼叫斑点猫头鹰时，横斑猫头鹰开始出现，并捕捉了他扔在地上的老鼠。这一行为说明了横斑猫头鹰已经侵入了斑点猫头鹰的栖息地，并对它们构成了威胁。 根据文章内容，我们可以确定当Stan Sovern呼叫斑点猫头鹰时，横斑猫头鹰（barred owls）会出现。因此，答案是D：barred owls appear（横斑猫头鹰出现）。