Photographing North America’s Rarest Bat

An endangered Florida bonneted bat, America’s rarest bat, once thought to be extinct.

America’s rarest bat, the endangered Florida bonneted bat (Eumops floridanus), was once relatively common. It often lived in tile roofs of Coral Gables and Miami, and its loud, low-frequency echolocation calls made it easy to detect. The species declined sharply in the 1950’s and early 1960’s, and by the late 1970’s extinction was feared. Then in 1978 woodcutters found a male and seven females in a woodpecker cavity. Soon several more were found living in a backyard bat house.

A pair of bat houses with pit-tag readers attached to monitor bat activity and movements.

Based on this discovery eight pairs of three-chamber nursery houses (See Bat House Builder’s Handbook) were mounted on poles in Florida’s Babcock-Webb Wildlife Management Area near Port Charlotte. Merlin was delighted to recently learn that all have been occupied by Florida bonneted bats. Each pair is occupied by an adult male, up to a dozen or more females, and sometimes also by a younger male.

Dr. Holly Ober from the University of Florida and Dr. Jeff Gore from the Florida Fish and Wildlife Conservation Center, aided by an outstanding team of volunteers, have joined forces in a long-term research project to better understand how to help this rarest of North American bats. We were invited to photographically document the bats to help promote their conservation.

Researchers prepare three sets of triple-high bat nets around a pair of 3-chamber bat houses.

At 3:30 PM on December 15 we hitched a ride with Holly in her 4-wheel-drive pickup, carrying some 75 pounds of photo gear for the 20-minute drive to the first night’s research site. Jeff and their team of volunteers had already erected what bat researchers refer to as “triple-high” bat netting poles, which enable three mist nets to be raised, one after the other to cover an area approximately 42 feet long by 30 feet high. Three sets formed a triangle around each of several pairs of occupied bat houses.

Project volunteer Dr. Ralph Arwood removes a Florida bonneted bat from a mist net.

Three work tents were pitched in which teams recorded weights, measurements and reproductive conditions and read “pit tag” information. All individuals that had been caught previously had had tiny “pit tags” inserted in fatty areas beneath the skin (like veterinarians do for dogs and cats so owners can be found easily).

Research project co-leader Jeff Gore and team member record pit tag information.

Since each bat house has been equipped with a tag reader, the researchers can record each bat’s activity times and movements among houses. Some 70 bats now living in area bat houses are captured and checked three times annually (spring, summer and winter). Relying on “pit tag” records, the team knows which bats have most frequently moved to alternative, presumably natural roosts. Finding these homes is crucial to understanding the species’ needs.

Jeff Gore examining a Florida bonnetted bat's patch of white fur on it's abdomen. Such patches of varied size and shape are common on this species, but not on its American relatives.
Unique, white belly markings are found on most Florida bonneted bats, but not on their nearest relatives.

The team’s primary objective for this trip was to attach radio collars and tiny transmitters to bats that had most often disappeared from their bat house roosts. In coming days volunteers would search for them with handheld antennas and receivers. Collars automatically break away in a few weeks.

Our job was to provide winsome photos of the bats and to document the research process in order to help win public support for their conservation.Merlin preparing to photograph the Florida bonneted bats.

There were plenty of challenges. Though these relatively large bats are especially gentle, that doesn’t necessarily translate to being easy to photograph! Merlin didn’t get a single useful picture of the first three bats. Then, just as he finally got one with a cooperative personality, heavy fog rolled in, taking him by surprise. His first good shots were ruined, and I painfully learned about Florida’s notorious “gallinippers,” huge, especially painful mosquitoes. Eventually, between patches of moving fog, lots of lens cleaning and mosquito swatting, we finally got the needed photos, the best of which will be returned to Florida in support of much needed public education.

Merlin and project co-leader Holly Ober inspecting road conditions.
Florida bonneted bats

An endangered Florida bonneted bat (Eumops floridanus) in Florida. This is America's rarest bat, once thought to be extinct.