They are very rare, 雪豹数量稀少

272. Seldom seen, the detail of their lives has long been a mystery,
     由于行踪隐蔽 雪豹的生活细节一直是个谜
273. but now, at last, helped by the latest remote-camera technology,
     但现在 借助最先进的远程摄像技术
274. we are getting closer to them than ever before.
     我们终于能够近距离观察他们
275. They are very rare,
     雪豹数量稀少
276. only about four of them in 40 square miles.
     百平方公里内只有四只
277. There is simply not enough prey to sustain more.
     只是因为猎物数量不足以维系更多的生命
278. They live solitary lives.
     雪豹是独居动物

来自《行星地球 第二季 第二集 Planet Earth S02E02 山脉》第 275 行