and then head back to the dust for no apparent reason. 数小时后就绝尘而去

178. in search of oases.
     其足迹早己遍布整个西藏高原
179. But when they do find paradise,
     当这些野驴真地找到了新的天地
180. they are liable to feed and drink for just a few hours
     饮水的饮水 吃草的吃草 个个毫无留恋之情
181. and then head back to the dust for no apparent reason.
     数小时后就绝尘而去
182. Wild ass are the most conspicuous pioneers of this high frontier,
     野驴是高原边疆上最明显的拓荒者
183. but the most numerous grazer in Tibet lives underground.
     但数量最为可观的食草动物却深藏在地下
184. Pika, a relative of the rabbit. It, too, feeds on grass.
     鼠兔 兔子的亲戚,和兔子一样以草为食

来自《行星地球 第一季 第七集 Planet Earth S01E07 伟大草原》第 181 行