This is, in addition to and when, natural sites are not available. Most likely to inhabit bat houses are little brown bats, big brown bats, eastern pipistrelle and the eastern long-eared bat. In the northern two thirds of the U.S. and Canada, most bats migrate south in the winter. Most bats that inhabit bat houses will move to caves, or mines. Tree roosting bats will fly south.
Bats find houses by sight.
If a house in the proper location, meets the requirements and is needed, the bats will move in on their own. The majority of bats that use houses are females using the house as nurseries. Research shows that they are more successful if they have at least 8 hours of sun. The morning sun is most important. Bat houses should face the south or southeast.