The smell of their own poo is being used to attract bats to a new home.
Burnley Council came up with the brainwave because a leisure centre often used by the creatures is being pulled down.
The bats aren't living there at the moment, but they will need somewhere to bring up their babies in the spring.
So the council is storing bat poo from the old nest and taking it to a new one in the hope that the creatures will follow their noses.
The Thompson Centre has been a favourite hiding place for the bats for some time.
It's being demolished in the New Year and council officials have found a nearby building that will make a new home for them.
"When the time comes for the bats to return, we can put the droppings in the new roost and the returning bats will pick up the scent," said a council spokesman.