Mexican free-tailed bats leaving maternity colony at night to feed, with red lighting at entrance to cave. Bracken Cave, USA

Mexican free-tailed bats (Tadarida brasiliensis) leaving maternity colony at night to feed, with red lighting at entrance to cave. Bracken Cave, San Antonio, Texas, USA, July. Bracken Cave is the world's largest bat maternity colony.

Mexican free-tailed bats (Tadarida brasiliensis) leaving maternity colony at night to feed, with red lighting at entrance to cave. Bracken Cave, San Antonio, Texas, USA, July. Bracken Cave is the world’s largest bat maternity colony.