Mexican free-tailed bats

Mexican free-tailed bats exiting Bracken Bat Cave

Image courtesy U.S. Fish and Wildlife Service Headquarters [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)],
via Wikimedia Commons

https://commons.wikimedia.org/wiki/File%3AMexican_free-tailed_bats_exiting_Bracken_Bat_Cave_(8006833815).jpg