TAMPA — People are bringing new energy to the Hillsborough River downtown thanks to the success of the Tampa Riverwalk — and that's bad news for bats.
As dusk falls, pedestrians who approach the Laurel Street bridge over the river are likely to hear the unmistakable flapping of tiny wings and glimpse shadows of the city's local bat population arriving for dinner.
Thousands of them can be found under the bridge, according to a Florida Fish and Wildlife Conservation Commission report — too close to the new crowds of people for either to be comfortable.
So about a year ago, Robin Nigh, the city of Tampa's arts program manager, went looking for advice on where to put a bat house that might draw away some of the creatures — one that's not just functional but aesthetically pleasing.
"None of us really knew a lot about bats," said Nigh, who turned to biologist Steve Barlow for help.
Barlow designed the renowned bat houses on the University of Florida campus in Gainesville, which provide shelter for hundreds of thousands of bats and are considered among the most successful in the world.
Francine Prager, who runs the conservation organization Tampa Bay Bats, also joined the effort.
The search effort settled on Julian B. Lane Riverfront Park, now undergoing a $35.6 million remake — close enough to water but far enough away from the densest parts of downtown.
Prager said there's really no reason people should worry about bats, on the Riverwalk or anywhere else. But they do, feeding misconceptions that the creatures are vicious, swarming bloodsuckers.
"They don't want anything to do with people," she said. "If they approach you, it's only because you have insects flying around you, whether you know it or not."
Julian B. Lane Riverfront Park is 23 acres of green space that was getting far less use than it should for its size and riverfront location, city planners said. In 2014, the city launched a major renovation. Slated for completion in March or April, the work will add new waterway access points, athletic spaces and a concert area along the next frontier of the Riverwalk — the west side of the Hillsborough River.
And now, it will include a bat house.
It must be built to strict specifications if the city hopes to tempt the creatures away from Laurel Street.
"One bat has to find it, like it and then tell the others about it," Prager said.
Bats communicate using audible clicks and whistles as well as echolocation — a sophisticated sonar-like system also used by dolphins.
The ideal bat house is 12 to 24 feet high, sealed tight to guard against weather and to maintain an interior temperature of 85 to 95 degrees. A proper landing pad is also critical to attract the bats.
The house must also be high enough off the ground and far enough away from trees to keep predators at bay, Nigh said.
"We had to work through all those things as the project evolved," he said.
Artist Lynn Manos-Page is designing the exterior for free. The new house will be a wrapped in powder-coated aluminum painted in tones of blue.
The city will foot the bill for the structure.
The two types of bats commonly found in Tampa are Mexican free-tailed bats, fast fliers with 11-inch wingspans, and evening bats, which are slower and have 8-inch wingspans, according to the Fish and Wildlife Commission report.
One objectionable feature of a bat colony is the smell of urine they excrete to mark territory, which the city hopes to cut down on by luring them away from Laurel Street.
On the flip side, a bat can eat up to 300 insects in a single night, eliminating thousands of crickets, mosquitoes and moths, and the creatures are essential to plant pollination.
Said Prager, "There are a lot of reasons to care about bats. They are fun and interesting to watch, and they were probably living here well before any of us were."
Contact Libby Baldwin at email@example.com. Follow her at @LibBaldwin