If there's a cave in New York that had 15,000 bats in it, and there are 1,000 left. That's like San Francisco becoming the population of half of this county in three years.
如果纽约的一个山洞里的15,000只蝙蝠， 只剩下1,000只了。 那就好像是圣-佛朗西斯科 的人口在三年内变成这个县城人口的一半。