Wait here at dusk anytime between March and October, and the concrete deck beneath your feet begins to stir with the largest urban bat colony in North America. Beneath this bridge live approximately 1.5 million Mexican free-tailed bats, the largest urban bat colony in North America. They arrived in the early 1980s when a bridge renovation created narrow crevices in the concrete deck — ideal roosting habitat for Tadarida brasiliensis, a migratory bat that summers in Texas and winters in Mexico.
When city officials first discovered the colony, there were calls to exterminate it. Instead, Bat Conservation International and local advocates convinced Austin to embrace its unexpected residents. Today bat watching is a major tourist attraction, drawing thousands of visitors on summer evenings.
The emergence begins slowly — a few scouts circling — then explodes into a churning ribbon of wings that can stretch for miles over Lady Bird Lake. The bats consume an estimated 10,000 to 30,000 pounds of insects every single night, making them critical to regional agriculture. Austin's bats turned a maintenance accident into a symbol of the city's willingness to find wonder in unexpected places.