It first starts with an incoming swoosh of cave swallows entering the cave for their nightly rest. Then in timed synchronization, the second and third set of swallows fly in taking up their spots within the cavern entrance.
Then a distant faint thunderous, fluttering noise is heard caused by thousands upon thousands of bat wings circling up into the opening of the cavern to begin their nightly feeding rituals. The swirling and spiraling starts like a reverse tornado in a mass of tiny mammals no larger than your thumb. Their continual motion resembles the sounds of a softly flowing stream.
Witnessing thousands of Mexican free-tailed bats (Tadarida brasiliensis) leave their dark roosts into a Maxfield Parrish painted sky is a phenomenal experience. Their swirling continues en masse as they continue to leave on their nightly feeding journey.
During this experience, a canyon wren started having a heck of a fit during the first part of the flight. It’s musical, metallic, loud voice was evident it was not happy getting caught during the bat flight. Adding to the experience a Northern Harrier began diving more than once in the mass of bats capturing his dinner.
The bats continued swirling out of the large cavern opening for an hour or more. Occasionally we’d hear some the hitting the cave walls as they left the cave. We witnessed this wildlife flight from inside a cavern entrance. Having some bats fly so close that you can feel the air pressure change in your face only added to the experience.
Mexican free-tailed bats are amazing mammal species who can fly up to 60 miles an hour with the help of a good tailwind. Forming the largest colonies of mammals in the world, they eat thousands of insects in a single night, including agricultural pests and mosquitoes. Their name derives from their tail protruding freely beyond the tail membrane.
An interesting fact – from 1903 to 1923, at least 100,000 tons of their guano was removed from Carlsbad Caverns National Park alone.
Note: This experience was at Carlsbad Caverns National Park.
Photograph – © Christena Stephens Photography