Largest urban bat colony

The world's largest urban bat colony can be found at the Ann W. Richards Congress Avenue Bridge in Austin, Texas, USA. Living underneath the bridge's road deck in gaps between the concrete component structures, the colony consists of Mexican free-tailed bats Tadarida brasiliensis, a migratory species that spends its summers in Austin. According to Bat Conservation International, between 750,000 and 1.5 million bats reside underneath this bridge each summer. The bats emerge from beneath the bridge at dusk each evening, and fly across Lady Bird Lake towards the east for food. This unusual daily ritual attracts as many as 100,000 tourists annually, resulting in an economic impact of $7.9 million per year.