The Congress Avenue Bridge bat emergence

An estimated 750,000 to 1.5 million Mexican free-tailed bats roost beneath the Congress Avenue Bridge and emerge nightly from spring through fall, creating a dramatic urban wildlife spectacle. This colony is the largest urban bat colony in North America and draws crowds who watch the synchronized evening exodus over Lady Bird Lake. The emergence is well-documented by biologists and city sources and is both a natural phenomenon and a widely told local 'strange' story. The site is used for educational programs and has become a notable Austin attraction.