What is a group of bats called?

There is no known group of bats called simply "a group of bats." The collective noun for bats depends on the context and often isn't a single, universally accepted term. However, depending on the situation, you might use terms like:

• A cloud of bats: This evokes the image of a large number of bats in flight, swirling together. This is probably the most evocative and commonly used collective noun.
• A colony of bats: This is suitable when referring to a group of bats living together in a roost, such as a cave.
• A swarm of bats: This is less common but works when the bats are moving in a chaotic, dense mass.

To give you more specific information about a particular group of bats, I need more detail. Do you have a specific species in mind, or a geographic location, or perhaps a specific behavior you're interested in? With more information, I can provide details about their diet, habitat, social structure, or conservation status.