This Creeped Me Out

When I got home I saw a pile of something in my driveway and noticed flies. I thought it was those liberal weiner dogs across the street, they have so many they wander in my yard, on my deck, etc. I am channeling the two hawks to pick them up and carry them off. When I went to look closer I thought it might be a baby bird but could not see a head. I thought maybe it fell but no upon on further look see, it is a bat. Where did it come from, how long has it been there, and are there more? Hmmm must keep on the look out, I don't want them in my house.