Arizona's Bridge Bats

“It's a wonderful sight, seeing them come out of there all at once,” says Charlie Panipinto, as he watches a cloud of Mexican free-tailed bats swirl out from under the bridge. These aren't the million and a half bats of America's largest urban bat colony at the Congress Avenue Bridge in Austin, Texas, but the bat bridges of Tucson, Arizona, are drawing a growing number of bat watchers like Panipinto.

Tucson's Arizona Daily Star newspaper described the evening emergences of bat colonies that live under more than a dozen of the city's bridges during the summers. It also used the occasion to dispel some myths and educate its readers with facts about bats and their benefits: their enormous diversity, the voracious appetites of some species for insect pests and the value of others as pollinators of plants, and the horribly exaggerated fear of rabies. And, of course, bats are great fun to watch.

“The mass evening departure,” Arizona Daily Star reporter Doug Kreutz writes, “is a little marvel of nature for bat-bridge regulars.” Hundreds, perhaps thousands, of free tails live under the North Campbell Avenue Bridge, the newspaper reports. But “the biggest bat brigade in the area” roosts under the East Broadway Bridge, with as many as 20,000 bats.

Tucson Wildlife Biologist Sandy Wolf told the newspaper that bats like to roost in narrow crevices that are sometimes built into the underside of concrete bridges. She said that 43 of the 238 bridges in the Tucson metropolitan area feature such crevices, and 35 of those bridges were occupied by at least one bat. Fifteen of the bridges were home to 100 or more bats, according to the newspaper.

Tim Snow of the Arizona Game and Fish Department says that, besides Mexican free tails, Tucson bridges provide homes to big brown bats, cave myotis, western pipistrelles and pallid bats. Some bats stay in Tucson year-round, he told the Daily Star, but most migrate to warmer regions for the winter.

But on summer evenings, more and more Tucson residents are taking advantage of what Snow called “the opportunity to see wildlife you don't normally see.” And some of them are becoming bat fans in the process.

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