Bats are usually social animals. Often they can be found living in caves. If you see one bat flying into a cave, you can be reasonably sure there are other bats inside. In some caves thousands of bats crowd together on walls or ceilings. Smaller bat colonies numbering only ten or twelve bats may live in a hollow tree.
Bats live in the pyramids of Egypt and in the fruit trees of Australia. In North America and Europe people sometimes share a house with bats and never know they are there. A bat can squeeze through narrow cracks and roost between layers of wall and ceiling.