Tadarida femorosacca (Merriam) in Tamaulipas, Mexico

In January 1946 a pair of naturalists entered a limestone cave ten kilometers north‑northeast of Antiguo Morelos in Tamaulipas, Mexico. Inside they found two pocketed free‑tailed bats—one lifeless, the other too weak to fly—lying amid a thick layer of guano. Their discovery pushed the known range of this elusive species hundreds of miles farther north than any previous record. The cavern’s high roof echoed with a chorus of squeaks when the explorers fired shots into its cracks, suggesting thousands of hidden bats were roosting within.

The brief report notes that the skulls of the two specimens measured just 18 mm in total length, smaller than any of the eight individuals previously described. Detailed measurements and a map of known localities help place this find within the broader picture of the species’ distribution. By describing the cave’s environment and the bats’ startled vocalizations, the authors give listeners a vivid sense of fieldwork in Mexico. The account leaves open the question of how many more colonies might be hidden in the remote hills, inviting curiosity about the secret lives of these night‑flying mammals.