I was watching a Miami Animal Police earlier tonight on the animal channel. It was from 2004, but they had a segment about rescuing 2 brown bats from inside a home. They mentioned about their droppings having a high level of ammonia in them. They took them outside behind a building and let them loose.
I have read several articles about bats being one of the best things to use to get rid of mosquitoes. You might want to build a bat house for them. :roll: