Congress Avenue Bridge bats

The Congress Avenue Bridge supports a large colony of Mexican free-tailed bats that roost beneath its spans. Estimates of the colony reach as many as 1.5 million bats in peak season, and it is widely described as the largest urban bat colony in North America. From roughly spring through fall, the bats emerge at dusk in large nightly flights that draw scientific interest and public viewing. The bridge and its nightly emergence are a notable natural and cultural landmark in downtown Austin.