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The History of Congress Avenue Bridge Bats in Austin

One of the best-known landmarks in Austin, Texas, is the Ann W. Richards Congress Avenue Bridge. The bridge, which is more commonly referred to simply as the Congress Avenue Bridge, crosses over Lady Bird Lake, which is impounded from Colorado River. The bridge has an interesting history, which is one of the reasons why it is such a well-known landmark. However, it is now best-known for being home to the world’s largest bat colony. Here is an overview of the history of Congress Avenue Bridge and the bats to which it is now home.

History Lesson

The first bridge in this location crossing the Colorado River was built between 1869 and 1871, and this was a pontoon toll bridge. It was replaced by a new wooden toll bridge in 1875 before it was replaced for a second time by an iron bridge designed by C.Q. Horton just nine years later. In the years following the reconstruction, the bridge was repaired on multiple locations and it was also repainted in 1902. As the population of Austin increased, so did the amount of traffic that crossed the bridge. This meant that the bridge was no longer fit for purpose, and construction of a new concrete bridge began in 1908. Construction was finally completed in 1910. In 1915 and 1922, some sections of this bridge were rebuilt, and parts of the old iron bridge were used to do this. The bridge as it stands now is one that was rehabilitated in 1980. When the rehabilitation took place, the structure of the concrete bridge was changed, and these restructures of the bridge had a surprising consequence.

Mexican free-tailed bats decided that the new crevices underneath the bridge were the perfect place for them to make a home, says Bat Conservation International. These crevices were ideal because they retained the heat of the daytime sunshine and stayed warm at night. What started as a few bats making the bridge their home eventually became a huge colony of bats. It is believed that the Congress Avenue bats are the largest urban bat colony anywhere in the world. It is estimated that there are between 700,000 and 1.5 million bats living under the bridge at any one time. To put the scale of this in perspective, there are often more bats living on this Austin bridge than there are humans populating the city. Austin has a population of approximately just over 950,000 people.

Unwelcome Visitors

At first, the bats were not a welcome sight in Austin. When they started moving in by the thousand, many people petitioned to have them removed from the bridge. While some people feared the bats, others were just ignorant about the species and saw them as pests. They were also concerned about the potential health risks of having bats living in large numbers in the city. Bat Conservation International helped to change people’s perception of the bats by educating them more about the species. This organization was founded in 1982 by Dr. Merlin Tuttle, a former bat researcher from the Milwaukee Public Museum. In 1986, Tuttle moved to Austin to further the educational program in Austin.

Those dwelling in Austin soon realized that they had nothing to fear. If the bats are not handled, then they are gentle and harmless creatures that pose no threat. They can even help the local environment as they eat up to 20,000 insects every night when they leave their colony, and this includes agricultural pests. Austin Monthly has revealed some more interesting information about Austin’s bat colony. The first thing that they note is that the bats do not live under the bridge all year. They only live there between March and early November, and they then return to their native Mexico between November and February. The bats that arrive in March are mainly pregnant females, and they create a maternity roost below Congress Avenue Bridge. Scientists say that the male bats of this species usually remain in Mexico. In the first week of June, the pregnant female bats give birth to one pup each. Following the birth of their pup, the females go out hunting at night to feed themselves and their pup. They predominantly prey on night-time insects.

Night Activities

Every night, a female bat can eat up to 75 percent of their body weight. Bat experts say that their favorite snack is the corn earworm moth. It is lucky they like to eat these insects because they are one of the worst crop pests in the United States, so the bats are doing everyone a favor. By ridding Austin of these pests, the bats are saving Texans millions of dollars in pesticides each year. Although there was a lot of concern about the bats living under the bridge when they arrived, public opinion has completely changed, and they are now considered an iconic part of Austin’s identity. Officials in the city continue to support programs that educate people about the bats and measures are in place to protect and conserve the Congress Avenue Bridge Colony.

Now, the bats that live under Congress Bridge have become a bigger attraction for tourists than the bridge itself. Tourists flock to the bridge at dusk each evening to watch the spectacular sight of the colony of bats taking flight. It is a fascinating sight to see, and many tourists photograph this phenomenal sight to commemorate their visit to Austin. It is captivating watching the bats fly, as they can reach speeds of up to 60 miles per hour and the fly as high as 10,000, which is significantly higher than any other species of bat flies. Despite Texas being home to 34 different species of bat, it is the Mexican free-tailed bats that are now most typically associated with this state, thanks to the Congress Bridge Colony. This is despite these bats being native to Mexico.

Lily Wordsmith

Written by Lily Wordsmith

Lily Wordsmith is a freelance writer who has had a love affair with the written word for decades. You can find her writing blog posts and articles while sitting under a tree at the local park watching her kids play, or typing away on her tablet in line at the DMV. In addition to her freelance career, she is pursuing ebook writing with an ever-growing repertoire of witty ebooks to her name. Her diversity is boundless, and she has written about everything from astrobotany to zookeepers. Her real passions are her family, baking desserts and all things luxe.

Read more posts by Lily Wordsmith

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