Congress Bridge Bats
Austin, the state capital and home to the University of Texas, is known as the “Live Music Capital of the World.” It also takes pride in being the “Bat Capital of the World“, being the spring and summer home for a million and a half Mexican free-tail bats.
Every summer night, hundreds of people gather to see the world’s largest urban bat colony emerge from under the Congress Avenue Bridge in downtown Austin, Texas. These 1.5 million bats are fun to watch, but they are also making our world a better place to live.
When engineers reconstructed the 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, Merlin Tuttle brought BCI to Austin and told the city the surprising truth
- that bats are gentle and incredibly sophisticated animals;
- that bat-watchers have nothing to fear if they do not 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 Congress Avenue Bridge population 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.
The Mexican Free-Tail Bat
Austin’s bridge bats are Mexican free-tailed bats. They migrate every spring from central Mexico and stop in various roosting sites throughout Texas and the American Ssouthwest. Most of the colony is female, and in early June, each one gives birth to a single baby bat. At birth, the babies weigh one-third as much as their mothers. This would be like a human giving birth to a 40 lb. baby.
The pink, hairless bats quickly grow. In about five weeks, with their mothers’ help, 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.
The Mexican free-tail bat (Tadarida brasiliensis) is relatively small, less than four inches in length with a wingspan of about 13 inches, and weighing less than a half-ounce. The name comes from the fact that the lower half of their tail, unlike other bats, is free of the membrane. They are one of the most numerous mammals in North America, and crucial to controlling agricultural insect pests, eating millions of Cotton bollworm and other small moths each night. They are known as the “jet fighter” of all bats, flying up to 60 miles per hour and reaching altitudes as high as 10,000 feet.
Seven hundred fifty thousand pregnant Mexican free-tail bats arrive in Austin in March and give birth in June. Their spectacular nightly emergence draws droves of tourists through October.
The Bat Colony at Austin’s Congress Avenue Bridge
As urbanization and other habitat encroachment has forced bats from natural roosting areas such as caves, the bats have adapted well to non-natural structures such as bridges and culverts. Expansion joints run under the Congress Avenue Bridge, and the Mexican free-tail bats have found these narrow crevices ideal roosts. Although only an inch wide, these joints can house as many as 200 bats in a single square foot of space.
The Texas Mexican free-tail bats winter in Mexico and migrate to Texas in March. About 750,000 pregnant females return to the nursing colony in Austin each year, making their home in the expansion joints under the Congress Avenue bridge. In June and July, each female bat gives birth to a single pup, and the young learn to fly five weeks later, joining the mothers in a nightly hunt for insects. Beginning in August, up to one and a half million bats emerge each evening. The bats emerge from under the bridge at sunset, putting on a show that lasts up to an hour. This show draws tens of thousands of tourists from March through October when the bats return to Mexico.
When and Where to See the Austin Bats
The Congress Avenue bridge crosses Lady Bird Lake (formerly Town Lake) just a few blocks south of the state capital. The primary city newspaper, The Austin American-Statesman, is headquartered at the south-east end of the bridge and opens its parking lot to bat-viewers each evening at 6:00 p.m. The paper maintains a park-like Bat Observation Center between the parking area and the lake. This grassy area contains interpretive signs and is ideal for watching the bats emerge from the nearby bridge.
The bats begin emerging as the sun sets, flying out from under the bridge and heading east above the lake. What starts as a trickle of bats quickly turns into a river of darting objects, hurtling out from under the bridge at 35 miles per hour and accelerating across the sky. This torrent of bats lasts perhaps an hour, well beyond the daylight needed to see them.
For current flight times, call the Austin American-Statesman information line, 512-416-5700, category 3636. Additional information can be obtained from Bat Conservation International (BCI). BCI is an Austin-based non-profit organization founded to protect and preserve bats and their habitat.
Congress Bridge Bats
Our friend, the bat.
In Austin, Texas, the people understand the bat. It wasn’t always that way, but through education and a study into how vital the bat is and how much the bat contributes to their area, the residents, at least most of them, have a genuine appreciation of the Mexican Free-Tail Bat.
They live in a colony, a rather large colony of 1.5 million bats. It has been calculated that theses bats eat between 30,000 to 40,000 insects each night when they leave their cave to forage for food.
The city of Austin is so grateful that they understand how beneficial the bat is to erect a statue to honor them.
It has increased tourism to those that want to see the mass exodus each night, and the Austin residents are glad to spread the truth about these much-despised creatures.
The more everyone learns about them, the more myth will be dispelled, and truth revealed how helpful they are to humanity.
Bat Conservation International (BCI) has been instrumental in protecting and promoting the now famous Congress Avenue Bridge bat colony as an eco-tourism destination. Still, 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. Now, the added mortality from White-nose syndrome and wind turbines, but persecution from humans remains a primary cause of their decline.
More Places to See Bats
Bracken Cave is the summer home of more than 20 million Mexican free-tailed bats (Tadarida brasiliensis), making it the world’s largest bat colony and one of the largest concentration of mammals on earth. The emergence of these millions of bats, as they spiral out of the cave at dusk for their nightly insect hunt, is an unforgettable sight.
Come join us near dusk (between 7:15 pm and 7:30 pm) underneath the Interstate 35 overpass at McNeil Road in Round Rock (located in front of Napa Auto Store), for a batty night of fun with the Round Rock Bats. Available free parking is located in the Napa Auto Store parking lot, and is first come, first serve. Don’t forget to bring blankets, covers, and a hat or some other head covering. And remember, never attempt to handle or capture bats at any time.
Eckert James River Bat Cave
Southwest of the town of Mason near State Highway 29 in Mason County sits the Eckert James River Bat Cave Preserve—one of the largest bat nurseries in the country. About 4 million female bats inhabit the site from May through September. This unique preserve is home to one of the largest aggregations of warm-blooded animals in the world.