What Does “A Colony of Bats” Mean?
“Colony” is the standard, well-documented collective noun for bats, and bat colonies can reach a genuinely staggering scale. Bracken Cave in Texas is home to an estimated 15 to 20 million Mexican free-tailed bats during peak summer months, widely cited as one of the largest concentrations of mammals anywhere on Earth, a single roosting site housing more individual mammals than many entire countries have people.
Colonial roosting offers real survival advantages: shared body heat helps bats conserve energy, particularly important for species that enter torpor, a temporary, energy-saving low-activity state, during cooler periods, and a large colony provides collective vigilance against predators. Maternity colonies, where females gather specifically to give birth and raise pups together, are especially important, since the combined warmth of thousands of bodies helps keep vulnerable newborn pups warm in roosts that would otherwise be far too cold for a lone mother to manage alone.
Example: “A colony of bats packed the cave ceiling by the millions, an almost unimaginable concentration of a single mammal species.”
Related: Collective Nouns for Mammals