Ann W. Richards Congress Avenue Bridge, Concrete arch road bridge on Lady Bird Lake in Austin, United States

The Ann W. Richards Congress Avenue Bridge is a concrete road crossing over Lady Bird Lake in Austin, Texas, carrying three lanes in each direction along with sidewalks on both sides. The structure links the southern and northern parts of downtown, serving cars, pedestrians, and cyclists each day.

The crossing opened in 1910, taking the place of earlier wooden and iron structures that had stood at this spot since 1869. In 2006, it received its current name in honor of the 45th Governor of Texas.

The bats are Mexican free-tailed bats, and the colony is a maternity roost: pregnant females arrive in spring and raise pups from mid-summer to fall, with males appearing only after the pups are born. The Austin Ice Bats hockey team took its name from them, and Ozzy Osbourne used the bridge bats in his "Patient Number 9" video.

Visitors gather along the shores of Lady Bird Lake before sunset from April through October to watch the bat colony emerge. The best vantage points lie below the span or on the east side, where the animals stand out against the evening sky.

Beneath the roadway lives North America's largest urban bat colony, with up to one and a half million Mexican free-tailed bats depending on the season. The animals use the gaps between the concrete beams as shelter and nursery space during the warm months.