Bracken Cave

Bracken Cave is a cave located in southern Comal County, Texas, outside the city of San Antonio. The 100-foot (30 m)-wide crescent shaped opening to the cave lies at the bottom of a sinkhole, formed when the roof of the cave collapsed. It 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 in the world. The cave and undeveloped 1,521 acres (616 ha) 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. Bat Conservation International bought the initial 697 acres (282 ha) from the Marbach family in 1992, and has been assisted in preservation efforts by The Nature Conservancy. 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.