Take a guided tour for an up-close view of Bracken Cave as millions of bats spiral out on their nightly insect hunt. Bracken is home to the world's largest bat colony and it is believed the Bracken Cave bats represent the largest concentration of mammals on Earth.

Take a guided tour for an up-close view of Bracken Cave as millions of bats spiral out on their nightly insect hunt. Bracken is home to the world's largest bat colony and it is believed the Bracken Cave bats represent the largest concentration of mammals on Earth.

Take a guided tour for an up-close view of Bracken Cave as millions of bats spiral out on their nightly insect hunt. Bracken is home to the world's largest bat colony and it is believed the Bracken Cave bats represent the largest concentration of mammals on Earth.