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with Frank Ridgley DVM, Zoo/Wildlife Veterinarian for Zoo Miami's Conservation & Research Department
Photo credit: Dustin Smith
Have you got bats in your home in South Florida? Check out our information sheet to help you know what to do: (English version) (Spanish version)
Not much is known about our largest and most endangered bat in Florida, the Florida bonneted bat (Eumops floridanus), compared to many other bat species in North America. It gained federal protection under the Endangered Species Act in October 2013. Its range is very limited to just the southern part of Florida and intolerance for cold temperatures keeps it from expanding northward. Unlike other bats in North America, it is more like a tropical bat species that doesn't hibernate.
There are still many questions about the Florida bonneted bat that need further research to answer. Florida bonneted bats have long narrow wings designed for very fast flight but are not adapted for tight turning. A comparison would be that all other native bats tend to be acrobatic in flight like moths while Florida bonneted bats could be compared to jet airplanes flying fast at high altitude in a straight line. This also means they tend to fly higher than other native bats and tend not to forage in areas where there are tight flyways or abundant obstacles. It is estimated that they could fly dozens of miles every night to forage. These characteristics make studying these species challenging for researchers since they tend to travel above traditional mist netting set ups they use to capture bats. In Miami-Dade County urban areas, Florida bonneted bats then must forage for food every night in a limited number of open spaces that remain in the urban landscape. Areas in the Miami-Dade County that they have been shown to utilize for foraging are golf courses, very large unlit parking lots, open fields in parks, airports, and large freshwater lakes.
These are two large chamber bat houses occupied by Florida bonneted bats in a preserve near Punta Gorda.
Florida bonneted bats tend to form small colonies with numbers ranging from just a few individuals to dozens. They appear to prefer to roost in cavities, whether natural or artificial. Known artificial roosts are in specially made bat boxes in Ft. Myers, Miami and near the Punta Gorda area and also in roofs of homes and condominiums in Coral Gables and Kendall. Natural roosts in tree cavities occur at the Florida Panther National Wildlife Refuge, Big Cypress National Preserve, Babcock Webb Wildlife Management Area and the Avon Park Air Force Range.
Florida bonneted bat roost under Spanish tile in Coral Gables
In Miami-Dade County, frequent hurricanes and habitat loss has eliminated most natural roost options of a large cavity in a dead tree. Therefore, it is likely that most of these highly endangered bats are residing in artificial structures like multistory buildings with gaps in wooden roofing or openings in Spanish tile roofs.
This is footage of a colony of Florida bonneted bats in a natural roost setting in a red cockaded woodpecker nest cavity in a slash pine at the Avon Park Air Force Range.
Zoo Miami’s Conservation and Research Department assists wildlife agencies in furthering the scientific knowledge of this special species. Staff conducted a year long acoustic study of Zoo Miami, Larry and Penny Thompson Memorial Park, and Martinez Pineland to determine if the Florida bonneted bat was present and possibly learn more about their use of these mixed use properties. The results from the study showed that the Florida bonneted bat is utilizing large open spaces on these county owned properties to forage for prey at night.
Did you know that Florida bonneted bat's vocalizations fall within the human hearing range unlike most of our other native bats that are ultrasonic? If you are female, and the younger you are, the greater the chance you can hear their calls at night flying overhead. Click below to hear a recording of them and see if you are lucky enough to be able to hear them.
Zoo Miami staff has also helped in the medical treatment, rehabilitation and release of many Florida bonneted bats accross their range.
This is a radiograph of an injured Florida bonneted bat that had a fractured repaired by Zoo Miami veterinary staff and was successfully released back to the wild.
Above is a radiograph of an injured Florida bonneted bat that happened to be pregnant and was successfully treated by Zoo Miami staff and released back to the wild.
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Zoo Miami veterinarians also assist the Florida Fish and Wildlife Conservation Commission in their studies of the Florida bonneted bat by conducting sonograms on females during permitted catch ups to try and find out more about fetal development and the reproductive characteristics of the species. See a segment of an ultrasound of a bat pup above.
“Bruce” the Florida bonneted bat pup that was hand raised by Zoo Miami staff and released back to the wild. Photo by Dustin Smith
Did you know that all bats are protected under wildlife laws? If you discover bats in your home, it is illegal to kill them. You can hire a pest control company to humanely exclude them from your home. They will put specially designed devices on the roost location entrance which will allow them to leave but not get back inside. Most colony bats in this area have multiple roost sites that they will switch between. That way they can safely leave your home and go to one of their other sites. In Florida, exclusion cannot be done between April 16th and August 14th because this is the maternity season for most native species and laws protect young from being separated from their mothers and dying of starvation. Unfortunately, these laws do not fully protect the Florida bonneted bat since they are believed to be able to give birth at any time during the year like is common with more tropical species. So, if you discover bats in your home, make sure that someone correctly identifies the species present to prevent Florida bonneted bat pups from being harmed.
Did you know Zoo Miami has over 30 bat houses on its grounds? They provide homes to hundreds of Brazilian free-tail and evening bats. One house has the potential to hold up to 800 bats. That single group could eat up to 21 lbs of insects in a single night!
If you want to help provide a safe habitat for our winged insect eating neighbors, consider putting up a bat house. These houses need to likely be placed >10ft high, with no obstructions nearby, facing north or south with sun exposure, and no access for predators. We recommend the use of a pivot pole support to enable easier installation and allow for maintenance, if needed. The area needs to be protected from potential disturbance and vandalism but might provide a refuge outside of homes where they could unknowingly be harmed from remodeling/construction and termite tenting.
In 2018, Zoo Miami undertook a new strategy for the urban Florida bonneted bats living in Miami-Dade County. There are no natural roosting locations known in Miami-Dade County but acoustical surveys and rehabilitation cases show that there is a fairly robust population of Florida bonneted bats around Miami-Dade County, including even the most urban core areas. To provide a safe alternative to roost, besides citizen's homes and businesses were the bats could be harmed or killed by roofers and termite tenting, Zoo Miami installed 16 hurricane resistant artificial roosts across the county in areas where high activity had been documented.
This strategy was designed to reduce human/wildlife conflict for the citizens of Miami-Dade County and provide these special bats safe harbor so they can continue to persist in Miami and help clean our skies every night while we are sleeping. The strategy proved to be a success and one house became occupied within three weeks! One year out from installing the array, seven out of the 16 boxes were occupied and pups were already being raised in several of them.
These installations were made possible by generous support from U.S. Fish and Wildlife Service, Bat Conservation International, Florida Sol Systems, Inc, Florida Power and Light, the City of Coral Gables, and the SeaWorld & Busch Gardens Conservation Fund.
In 2019, Florida Power and Light, Bat Conservation International and Zoo Miami's Conservation and Research Department have teamed up to form the FPL Bat Lab at Zoo Miami. This new lab is based at Zoo Miami and is dedicated to solving some of the ecological issues for the federally endangered Florida bonneted bat, especially the unique urban populations in Miami-Dade County. To head up the joint program, BCI recruited Dr. Melquisedec Gamba-Rios to help design and execute some of the research protocols to solve some of the mysteries surrounding #ourendangeredneighbor. With the new lab, a new website was also launched to serve as a centralized resource for the project Miamibatlab.org.
To check for occupation of the artificial roosts that were installed around Miami, we must use a small camera on a very long telescoping pole.
When we are checking a previously unoccupied house, sometimes we get lucky and get a great video like the one below.
Here is some media coverage about the species and our program:
Miami New Times October 30, 2019
Journal of Fish and Wildlife Management July 25, 2019
Coral Gables Magazine April 2, 2019
Miami Herald March 11, 2019
WLRN Sundial December 11, 2018
Miami Herald June 14, 2015
South Dade News Leader December 31, 2014
WCS Wild View October 17, 2014
TurfNet July 8, 2014
NBC Miami March 24, 2014
CBS Miami March 24, 2014
To hear a talk given to the Audubon Everglades chapter by Dr. Frank Ridgley on the bats of South Florida, click the videos below.