extensive, a way must exist for these bats to continuously congregate in the same roosts every year. T. brasiliensis bats have copious numbers of sebaceous glands covering their entire bodies. These glands leave a trace of a lasting scent to which other bats are sensitive. This odor is crucial to marking habitual roosts. Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally. Also, a regional population that ranges from Oregon to California, has a year-round residence. Diet Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. They usually catch flying prey in flight. Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects. The consumption of insects by these bats can be quite significant.Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum The onset of evening emergence from caves and the end of returns at dawn tend to correlate with sunset and sunrise, respectively, with dawn returns ending increasingly later in correlation to sunrise throughout the summer season. Reproductive females tended to emerge earlier in the evening and return later at dawn to gather the extra nutrients they require for reproduction and offspring care. T. brasiliensis bats spend around 60% of their active time foraging while aerial, mostly hunting at heights of . Individuals will fly in one night to reach foraging areas. The loose, wrinkled skin around the mouth is thought to aid in expanding the mouth during flight to catch insects. T. brasiliensis requires free water sources to maintain water balance: individuals from the arid environment of New Mexico tend to have thicker renal tissue layers compared to T. brasiliensis from the less arid California, revealing that urine concentrating abilities and water use varies geographically with aridity. Health and mortality One individual bat was recorded to have lived 8 years, based on dentition. Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites. Mammal predators include Virginia opossums, striped skunks, and raccoons. Snakes such as eastern coachwhips and gopher snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground. This species seems to have a low incidence