This photo is a louvered vent; a favorite entry for a lot of bats. Once inside the cozy attic space, bats will have their young and increase the colony size.
Bats are known to carry rabies and their guano(droppings) are a source of disease as well.
Signs of bats in a home or building could include hearing squeaking sounds or mouse like droppings on the side of the wall or on the ground below a suspected entry point.
If you think you have bats in your residence or building, visit this link for a pro in Potter County.