Austin’s Ann W. Richards Congress Avenue Bridge, also known simply as the Congress Avenue Bridge, houses around 1.5 million Mexican free-tailed bats during the hot summer months. The bats congregate under the bridge that leads to the Austin Capitol Building and take flight in large groups as dusk approaches. The flight of the bats makes for a popular tourist attraction during Texas summers, when evenings are warm and the largest volume of bats lives under the bridge.
What is a Mexican Free-tailed Bat?
These South Congress Bridge bats are descendants of two closely related bat species: the Chaerephon Jobimena species originating in Madagascar, and the Tadarida Aegyptiaca species that makes their home in Africa and south Asia.
Characteristics
They reach about 9 cm in length, but half of that length is composed of their characteristic tails. They are called “free-tailed” bats because their tails extend past the webbing between their legs that helps them fly.
A healthy bat weighs about 12 grams. Their fur can be anywhere from red to dark brown and even gray. Their large and wide-set ears provide them with superior skill in echolocation, and their long, narrow wings with pointed tips help them travel fast in a straight flight path.
Habitat
South Congress Bridge bats originated in Mexico, where the weather is warm and allows for insect populations (the bats’ main source of food) to grow year-round. But the milder Texas summer and ideal living conditions have driven the bats to Austin, TX since the bridge was completed in the 1960s.
Today, the bats spend the hottest summer months perched underneath the Ann W. Richards Congress Avenue Bridge. Insect populations that breed in the Colorado River, which runs perpendicular to the Congress Street Bridge, keep the bats fed for the entirety of their stay. They eat anywhere between 10,000 and 30,000 pounds of insects every night.
The shade from the bridge and cool breeze from the water provide all-day comfort, and the bats are free to roam once the sun sets. They are harmless to humans and have a low incidence of rabies.
Bat Viewing in Austin, TX
About 100,000 tourists visit Austin annually to see the flight of the bats as they set out to feed at dusk. As the largest urban bat colony in the United States, the Congress Street Bridge is one of the only places tourists can see such a large volume of bats fly out to feed.
During the Texas summer, tourists and locals alike gather on the grass next to the Colorado River to watch the bats fly. Typical Texas summer sunsets occur around 8:30 PM, but space next to the river fills up fast. Bat viewers are encouraged to bring:
- Blankets
- Chairs
- Bug Spray
- Hats
Hats are recommended to keep potential bat droppings from affecting the viewing experience. Visitors are asked not to disturb the natural habitat of the bats. Please avoid:
- Touching the bats
- Feeding the bats
- Littering
Such a large population of bats is rare in an urban area. The City of Austin is eager to protect this natural phenomenon.
During the Texas summer, tourists and locals alike gather on the grass next to the Colorado River to watch the bats fly. Typical Texas summer sunsets occur around 8:30 PM, but space next to the river fills up fast. Bat viewers are encouraged to bring:
- Blankets
- Chairs
- Bug Spray
- Hats
Hats are recommended to keep potential bat droppings from affecting the viewing experience. Visitors are asked not to disturb the natural habitat of the bats. Please avoid:
- Touching the bats
- Feeding the bats
- Littering
Such a large population of bats is rare in an urban area. The City of Austin is eager to protect this natural phenomenon.