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Volume 7, Issue 1, Spring 1989

Found and Lost: The Rare Florida Mastiff Bat

A Florida mastiff bat (Eumops glaucinus floridanus) hadn't been seen for ten years when last September, one was discovered on a seventh floor balcony of an office building in Coral Gables, Florida. Fortunately for the bat and for researchers, it was discovered by people who cared enough to make a few phone calls. The Florida Game and Fresh Water Fish Commission sent Mark Robson, who only knew that some kind of bat had been found. Discovering the rare bat when he arrived was a major surprise. A few months before, he and Frank Mazotti, an urban wildlife expert at the University of Florida, had started to explore and inventory Florida's bats, especially searching for evidence that the Florida mastiff bat still existed.

The bat found was a female and in trouble, dehydrated, and only semi-conscious. She was rushed to a local veterinarian, Dr. Theresa Parrott, who fed her fluids intravenously. Then an x-ray showed the bat to be pregnant--good news, everyone thought. That meant there was at least one other mastiff bat (the father) and soon there would be a third. At first it was believed that the pregnancy was near term, but after several days in captivity, the bat aborted a fetus and began a rapid recovery, becoming quite active and vocalizing loudly. Since it still needed considerable care, Dr. Parrott had taken her "star patient" home over the weekend. Unfortunately, as the bat recovered, she had other ideas and escaped. Despite an intensive search, she was not found. She escaped about 12 miles north of where she first was found, and since mastiff bats are strong and fast fliers, it can only be assumed that she made a successful getaway and was able to return to wherever she came from.

The Florida mastiff bat was recently declared a candidate for listing as an endangered species by the U.S. Fish and Wildlife Service. Robson is now working with the USFWS on designing a more intensive survey to locate these rare bats and determine their status. The survey will begin in late spring of this year and will continue through fall, focusing on the historic range in southern Florida. Previous known roosts will be revisited and attempts to locate new ones will be made. One of the difficulties in finding bats of this genus is that they tend to roost and feed high above the ground where they are unlikely to be noticed.

In 1978, the last year that mastiff bats were seen in Florida, a small harem was found in a woodpecker cavity in a tree, consisting of one male and seven females. Of the females, five were post-lactating, and one was pregnant, indicating that although rare, they were reproducing. The new survey will be the first intensive attempt to document the status of this bat in Florida.

This Eumops glaucinus glaucinus is closely related to Florida's rare mastiff bat, to be the subject of an intensive search beginning this spring. PHOTO BY MERLIN D. TUTTLE

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