A network of caves, many of which are thoroughly inaccessible to humans, runs underneath much of the town in which I live. There must be an opening somewhere near our house, though. Many times in the summer we’ve seen groups of bats take to the sky around dusk from somewhere beyond our back yard. It’s an impressive sight.
Now that I think about it, I remember seeing fewer bats last summer than in the previous several years. I hope this isn’t the reason why.