Originally posted by Nerevar:

never saw bats attack my base. only saw bats in frost caves so far. maybe they come after the queen?

they were added same time the frost caves, and it the same 1 damage per hit guys, X about 30 at a time or something annoying. They don't damage the base much, if at all, what they do is sucker you into wrecking the place by going all zerker on them and hitting everything in sight. Step outside, and lay about away from anything you built, and its over in moments, load up the skins into the obliterator and call it a day.