Ann W. Richards Congress Avenue Bat Bridge

The Congress Avenue Bridge features long, deep concrete crevices beneath its deck that mimic the dark, narrow caves bats naturally prefer for roosting. When engineers redesigned the bridge in nineteen eighty, they unwittingly created the largest urban bat colony in North America. By late summer, one and a half million Mexican free-tailed bats emerge from these expansion joints at dusk. Visitors gather on the banks to watch the massive, swirling cloud of mammals spiral south across the water to hunt insects.