英语听力:自然百科 走进西藏 tibet—13(在线收听

 In such a frugal environment, the Pika's farming helps to kickstart the food chain. But the Pika itself is a very tasty morsel. Its presence has enabled an uneasy relationship to develop between the two plateau most opportunistic predators, the fox and the bear. 

 
The Tibetan brown bear, a close relative of the grizzly, trys to dig the Pikas out from their burrows, even hard, frozen soil presents little obstacle to a determined bear. The wily Tibetan fox is quick to spot any opputunity. True to form, the crafty fox claims the prize. 
 
A combination of inaccessabily and ancient traditions, which forbid hunting, means that in some parts of the plateau, wild aninals have remained relatively undisturbed, even today.
 
But in those areas which are within reach of motor vehicles, these historical safeguards have been undermined. 
 
These changes is illustrated in the fortunes of the chiru. A century ago, millions migrated cross the plateau. Unfortunately, for the chiru, its fur, knowm as shartoosh ,or  King of wools,  is highly prized . In recent decades, purchase are being able to adventure deep into the wildness killing thousands of chiru. however, the situation is improving, anti-poaching laws are now actively enforced, so every summer female chiru can head to the birthing grounds in relative safety.
  原文地址:http://www.tingroom.com/lesson/zrbaike/2010/259314.html