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. Scientists learned about the barred owl migration by__.
A、decoding spotted owl sounds
B、feeding mice to the owls
C、monitoring spotted owl populations
D、researching the Internet
【正确答案】：C
【题目解析】：根据文章内容，科学家对斑点猫头鹰（spotted owl）的研究是通过观察其数量变化以及与其他猫头鹰（如横斑猫头鹰barred owl）的交互来进行的。文章提到，由于横斑猫头鹰（barred owl）的迁移和出现，斑点猫头鹰的数量开始减少，并且有些横斑猫头鹰和斑点猫头鹰还进行了杂交。这表明科学家是通过监测斑点猫头鹰的种群变化来了解横斑猫头鹰迁移的情况。 A选项“解码斑点猫头鹰的声音”在文章中并未提及，所以不是科学家了解横斑猫头鹰迁移的方式。 B选项“给猫头鹰喂食老鼠”只是文中提到的一个具体实验场景，而不是科学家学习横斑猫头鹰迁移的主要方式。 C选项“监测斑点猫头鹰的种群”与文章描述的内容相符，科学家通过监测斑点猫头鹰的种群变化来了解横斑猫头鹰迁移的影响。 D选项“研究互联网”在文章中完全没有提及，因此也不是科学家学习横斑猫头鹰迁移的方式。 因此，正确答案是C，即科学家是通过监测斑点猫头鹰的种群来了解横斑猫头鹰迁移的情况。