When the person I live with was much younger, she lived in Minnesota. There was a huge bat colony in the attic. Her parents didn't like the bats, and tried to block all holes in the eaves, so that they couldn't get back into the house after their night's foraging. Her father worked all day to close up the holes, and then fitted a one-way vent (from a clothes dryer) to the place where they usually exited.
As dusk fell, her family sat in the car with the lights turned onto the roof, and counted the bats coming out through the one-way vent. There were dozens. But the next night, the bats all came out again through the one-way flap, as they had managed to find a way back in at dawn. The Bat Wars went on for weeks, with harsher and harsher methods. At one point, the bats started coming into the house through the heating grids in the floors. No-one much liked that. The story ended badly for the bats. In an interesting side note: the bats had been in residence for decades, and their gauno had piled up in the attic. My friend’s mother, who was a keen organic gardener, was very happy with this source of free fertiliser.