I guess we have bats nearby. I have seen them flying around every now & again & the cat bought one into the house once!!
We thought first of all it was a dead leaf, until it unfolded it's wings and started crawling about the floor! Managed to get the cat out of the house & the bat then took off and hung itself from the rail that goes round our living room (tasteful (not) dado rail that previous owner put in).
It then started doing loops of the room before hanging from the rail again.
I had the computer on so got on the internet & found a bat expert based nearby (who'd have thought!!). I called them up, but they had settled down for the evening with a bottle of wine so were unable to come out & collect it. I explained that it was currently hanging on the wall & appeared to have a fairly large tear in it's wing.
The woman then proceeded to lecture me that it's an offence to hold a bat in captivity! I asked her if she would prefer me to give it back to the cat (the cat was well miffed we deprived her of her new toy!)
In the end she said it was probably OK to fly with the tear in the wing & to catch it and let it go. Catching it was difficult, but in the end we used a sieve. The bat seemed to be able to sense that something was there, but not exactly what & we managed to coax it into a box (which it did a few poos in).
I then walked it down the road to a large field & let it go…..it flew off & that was that!
Quite a fun evening!