Congress Avenue Bridge bats (largest urban bat colony in North America)

The Ann W. Richards Congress Avenue Bridge in downtown Austin shelters a colony of Mexican free-tailed bats long described as the largest urban bat colony in North America. Estimates of the colony's size vary by year and counting method, with some estimates reaching around 1.5 million bats. The bats roost beneath the bridge and typically emerge at dusk from March through November, creating a widely observed nightly spectacle.