What kind of bats are referred to as “colonial bats”?

Colonial bats are species known for their social behavior, where they congregate in large numbers, often in specific roosting locations. This tendency to form colonies is typically advantageous for various reasons, such as enhanced protection from predators, improved thermoregulation, and more effective communication among members of the group. Being part of a colony allows these bats to share warmth, help in foraging, and engage in social interactions that are beneficial for their survival and reproduction.

The other options describe behaviors that are not associated with the "colonial" designation. Bats living alone do not exhibit the social characteristics that define colonial bats. Migrating bats travel from one location to another, often in response to seasonal changes, rather than staying in a consistent roosting group. Bats that hibernate are focused on surviving through cold months and do not exhibit the active social structure characteristic of colonial living during this time. Hence, the defining characteristic of colonial bats is their tendency to congregate in groups, making them distinct among bat species.