for National Geographic News
Walk near the Congress Avenue Bridge in Austin, Texas, on a summer evening, and you'll be tempted by bat T-shirts, bat photographs, and bat paraphernalia in all shades of black. Nearby hotels tout rooms for their outstanding bat views.
It's all part of an industry that has sprung up around the city's nightly bat emergence, when an awe-inspiring colony of some 1.5 million Mexican free-tailed bats flee their bridge roost each evening at dusk.
The spectacle began after the bridge was renovated in the 1980s to include deep, narrow crevices on its underside that were unintentionally ideal for bat nesting.
Today the bridge draws tens of thousands of tourists when the bats are in residence (from March to October) and contributes an estimated eight million U.S. dollars to the local economy.
"It has really become integrated into the culture," said Barbara French, biologist with Bat Conservation International (BCI) in Austin.
"Even the hockey team is named the Ice Bats."
The bridge is a unique attraction, but it's also a blueprint for ongoing efforts to convert bridges, highway culverts, and other suitable locales into new bat habitat.
"One of the ways that people are working to mitigate the loss of natural habitat is through the development of artificial roosts," French said.
Same Bat Station?
The Texas Department of Transportation currently outfits dozens of bat-friendly bridges per year.
"Particular bridges have expansion joints in the bottom of the bridge that are about three-quarters of an inch [1.9 centimeters] wide and 12 inches [30.5 centimeters] deep," said Meg Goodman, bat biologist with the Texas Parks and Wildlife Department (TPWD).
"These crevices are just the right size for bats."
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