Having bats in attic spaces is very common. Bats are essentially nothing but cartilage and fur, making it extremely easy for them to get through the smallest of openings, as small as ½”.
Aside from the high pitched squeaking, and the droppings that people find on the exterior of their homes from gable vent areas, some people don’t know that having bats in their homes can actually be hazardous to their health.
Not only can bats potentially carry rabies, but bat droppings (guano) can be toxic to breathe. Bats in an enclosed attic setting can quickly produce enough guano to become hazardous. If you discover bats in your attic, not only should you call a trained professional to remove them, but you may also want to consider removing and replacing any soiled insulation.