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Congress Avenue Bridge

A Little History

Every summer night, hundreds of people gather to see the world's largest urban bat colony emerge from under the Congress Avenue Bridge.These 1.5 million bats are fun to watch, but they're also making our world a better place to live.

When engineers reconstructed downtown Austin's Congress Avenue Bridge in 1980 they had no idea that new crevices beneath the bridge would make an ideal bat roost. Although bats had lived there for years, it was headline news when they suddenly began moving in by the thousands. Reacting in fear and ignorance, many people petitioned to have the bat colony eradicated.

About that time, BCI stepped in and told Austinites the surprising truth: that bats are gentle and incredibly sophisticated animals; that bat-watchers have nothing to fear if they don't try to handle bats; and that on the nightly flights out from under the bridge, the Austin bats eat from 10,000 to 20,000 pounds of insects, including agricultural pests.


As the city came to appreciate its bats, the population under the Congress Avenue Bridge grew to be the largest urban bat colony in North America. With up to 1.5 million bats spiraling into the summer skies, Austin now has one of the most unusual and fascinating tourist attractions anywhere.

The Austin American-Statesman created the Statesman Bat Observation Center adjacent to the Congress Bridge, giving visitors a dedicated area to view the nightly emergence. It is estimated that more than 100,000 people visit the bridge to witness the bat flight, generating ten million dollars in tourism revenue annually.

A Little Background

Austin's bridge bats are Mexican free-tailed bats. They migrate each spring from central Mexico to various roosting sites throughout the southwestern U.S. Most of the colony is female, and in early June each one gives birth to a single baby bat, called a pup. At birth the babies weigh one-third as much as their mothers (the equivalent of a human giving birth to a 40-pound child!).

The pink, hairless babies quickly grow. In about five weeks, with the help of their mothers they learn to fly and begin to hunt insects on their own. Until that time, the mothers nurse their babies, each locating her pup among the thousands by its distinctive voice and scent.

A Big Challenge

Bat Conservation International (BCI) has been instrumental in protecting and promoting the now famous Congress Avenue Bridge bat colony as an eco-tourism destination, but as our name indicates, we work worldwide to protect bats and their habitats. Despite the popularity of the bridge bats in Austin, bats are still among the world's least appreciated and most endangered animals. Like other wildlife, bats suffer from habitat loss and environmental pollution, but persecution from humans remains a primary cause of their decline.

A report on the success of BCI's environmental education efforts at the Congress Avenue Bridge in 2006 can be found here .

For additional information on the fiscal impact of the Congress Avenue Bridge Bat Colony on the City of Austin, you can download this report.

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Last Updated: Thursday, 10 October 2013
Unless otherwise noted, all images are copyright ©Merlin D. Tuttle and/or ©Bat Conservation International