Bats feed at night (they are "nocturnal") and spend the day sleeping in caves or in tree tops. The place where a bat sleeps is called its "roost".
Bats hang UPSIDE DOWN from their roosts when they sleep.
Although some bats roost in groups of only one or two, for the most part bats are very sociable animals. They usually sleep together in huge groups.
Some caves may be home to thousands of bats. The largest bat colony in the world is in Bracken Cave, Texas. During the summer, this cave is home to as many as 20 MILLION Mexican free-tailed bats. That's a LOT of bats!