South Texas’s Bracken Cave is home to 15 million Mexican free-tailed bats (Tadarida brasiliensis) — the world’s largest known bat colony — and their use of the cave is changing dramatically. In the 1950s, researchers observed no bats in December and January. Today, more than 50,000 bats emerge in the winter — sometimes more than 250,000 of them. “That’s a very sudden change—to have no animals there, to having some, to having so many,” researcher Phil Stepanian told the New Yorker. Stepanian believes the change is likely due to prey availability as a result of warmer winters, raising the possibility of a mismatch between bats’ migration timing and the arrival of prey.
Read more in the New Yorker.