by Mark and Selena Kiser
The Wagner's bonneted bat is Florida's largest and rarest bat. Listed as endangered in Florida, it occurs only in the southernmost tip of the state. With a wingspan of up to 18 3/4 inches, it is about 70 percent bigger than the Mexican free-tailed bat. Wagner's bonneted bats (formerly known as Wagner's mastiff bats) roost in Spanish tile roofs, tree hollows and dead palm fronds. Colonies are small, with the largest reported at just 32 individuals.
In Florida, this species has been seen only a few times since the 1960s, mostly in the Miami metro area. Habitat loss and heavy pesticide use are believed responsible for the decline. The last-known roost was the hole of a pileated woodpecker in a longleaf pine tree in Charlotte County. This tree, which contained eight bats, was cut down to make way for a road construction project in 1979. In the 1990s, a few injured individuals (including a pregnant female) were found and taken to wildlife rehabilitators, but no roosts were located.
But an exciting discovery was made last year - one that has great potential for this species. Susan Trokey, a biologist with the U.S. Fish and Wildlife Service, installed a single-chamber bat house in her backyard in Lee County in June 2000. Mounted on a pole 17 feet above ground, it had a 1 1?2-inch roost chamber with a 3?4-inch opening. Up to 75 Mexican free-tailed bats used the house for three years.
Then, one evening in February 2003, the Trokeys noticed several large bats emerging from the house. Convinced they were of a different species, Susan asked Cyndi and George Marks with the Florida Bat Center to investigate. They recorded the echolocation calls with a bat detector and later netted one of the mysterious bats as it emerged. To everyone's surprise and delight, the bat was a Wagner's bonneted bat.
Not only was this the first roost located in 24 years, it is also the first time a Wagner's bonneted bat has been reported in a bat house, which gives reason for optimism about the future of this species.
An estimated 11 bonneted bats, including an albino, used the bat house last year, and now the Trokeys are testing three new houses, each with a different chamber spacing, to determine if these bats have a preference.
Stay tuned for future updates.
