only about four of them in 40 square miles. 百平方公里内只有四只
Mothers show the cubs what to do about this. 母熊给小熊们做了示范
They take a fairly relaxed view about what constitutes a nest. 它们筑巢并不讲究
From a single ancestor, about a hundred different types have evolved. 他们从同一个祖先 进化出一百个不同的种
need only about a tenth of the food a carnivorous mammal would. 肉食性哺乳动物十分之一的食物量
and she won't mate again until it leaves her in about six months' time. 在幼崽六个月后长大离开之前 她不会再次交配
But there's something special about this stretch of forest in Uganda. 乌干达的热带雨林有些特别