Bats are one of the most feared animals on the north American continent. Here in the North East the two most common bats found in houses are the little brown bat and the big brown bat. believe it or not the bat is one of the most gentle creatures in the animal kingdom. it is our only flying mammal. The bat is not aggressive at all. Most wild animal mothers will kill, abandon or even consume their young when put under extreme stress, I have never heard of any bat following these traits.
Most people realize that they have bats when they hear the bats crawling in their walls or ceilings, Find bat droppings in their attic or around the outside of the house or they get a lost bat in the house.