Add Yahoo as a preferred source to see more of our stories on Google. Bracken Cave in Texas is home to 15-20 million Mexican free-tailed bats. Female bats head to the cave every year to give birth.

Florida is home to 13 native bat species and, while they usually roost in natural areas, such as trees, caves and similar spaces, they sometimes take shelter in human-made structures.

Every evening, millions of bats swarm out of a single cave in Texas, making it one of the most stunning natural phenomena to witness. The colony is so huge that it turns the sky black as they begin ...