Bracken Cave

Bracken Cave is the summer home to the largest colony of bats in the world. An estimated 20 million Mexican Free-tailed Bats roost in the cave from March to October making it the largest known concentration of mammals. The cave is located in southern Comal County, Texas, outside the city of San Antonio. The 100-foot-wide crescent shaped opening to the cave lies at the bottom of a sinkhole, formed when the roof of the cave collapsed. The cave and 697 undeveloped acres around it are owned by Austin, Texas-based Bat Conservation International, which restores the land to support native vegetation and an abundant variety of wildlife. Access to the cave is restricted to protect the habitat of the resident bats. Bat Conservation International offers evening guided tours to the cave to watch the bats emerge from the cave. Despite its protected nature, Bracken Cave has been featured in the media several times since its discovery. National Geographic Wild HD channel included Bracken Cave in its World's Weirdest Series, Episode: Freaks of the Sky. The Bracken Cave is the destination every March or April of over 20,000,000 Mexican Free-tailed bats (Tadarida brasiliensis). These bats fly as much as 1,000 miles from Mexico to this cave. After arriving in the cave, the migrant mothers give birth to pups. An astounding 500 pups have been recorded clinging to one square foot of the cave walls—an ingenious way for keeping warm.