near midway airport and oak lawn, i notice the same bird /bat like sounding animal flying around during the day. It makes a high pitched squeak as it flies.is it a bat or swallow? I don't notice the 2 tails though.
Visiting Extension Specialist, Pollution Prevention
Extension-Illinois-Indiana Sea Grant College Program firstname.lastname@example.org
I'm guessing that you are seeing chimney swifts. They make a very high-pitched chattering noise, they are fairly small, and their flight pattern does sort of seem bat-like.