Most bats are nocturnal. This means that they are active only at night. They sleep in the daytime and come out at night to find food. Only a few kinds of bats venture out in bright sunlight. Bats are probably night creatures for the same reasons that most small mammals are. A small animal is in less danger at night. In the daytime it is in constant danger of being eaten by larger animals that sleep at night. Also, at night bats can catch insects with less competition from birds.