英语听力：自然百科 黄石公园的夏天 Yellowstone—7（在线收听） |
Hot water scorches and drowns the roots of trees encroaching on the valleys. It can keep the forests in check and the rich pastures / open. Those pastures now produce the new grass needed to make rich milk and feed a bison baby boom. The few calves born on the migration are now joined by hundreds of new youngsters. The predators have been waiting for this. Coyotes have a voracious reputation here. But on its own this one is certainly no match for a healthy bison and her calf. Pronghorn give birth to twins, each carefully cleaned to hide their smell from predators. While they are with her, they are relatively safe. And for now, the coyote is content with the afterbirth. But the mother pronghorn must leave her calves alone while she grazes. And with legs as wobbly as stilts, their best defense is to lie low. She has young of her own to worry about, a demanding litter of nine, whose arrival has been carefully timed to coincide with an abundance of food.
But they are not top dog here. Yellowstone's top predator, the wolf, dominated during the winter but is far less visible in summer. They prefer to stay close to well-hidden dens to protect their pups from... |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2012/273744.html |