Did you know birds sound like bats?
I actually am surprised this isn't common knowledge. One of our house used to be infested when I was a kid.

"It turns out bats (some bats anyway) sing — sing uncannily, spookily, like songbirds, with the trilling, the chirping, as if they were nightingales."
http://www.npr.org/sections/krulwich/2014/10/01/352586936/is-that-a-lark-i-hear-a-nightingale-surprise-its-a-bat

:bat: :bird: