Credit: Photo courtesy Daniel Greene, a Ph.D. student for UF scientist Robert McCleery.
Robert McCleery, UF assistant professor in wildlife ecology and conservation and co-author of the study, estimated that fewer than 500 of the woodrats remain.
That's down from U.S. Fish and Wildlife Service estimates of about 6,000 in 1984.
Federally endangered Key Largo woodrats are important to the ecosystem because they spread seeds in a unique forest ecosystem, their stick nests create shelter and habitat for other species and they are important prey for other species, such as snakes and hawks.
Researchers simulated what woodrats would do in the wild, how they behave in captivity and what happens when they're released back into their natural habitat, said McCleery, a faculty member in UF's Institute of Food and Agricultural Sciences.
"When we kept looking at the data, what we found was that you really couldn't breed enough woodrats to make it a viable strategy for population recovery," he
Woodrats usually reproduce in the wild, two times a year, with litters of three or four, McCleery
In captivity, they averaged less than one offspring per female per year, he
When some animals are not in their natural environments, meaning they don't eat their usual foods or respond to their usual cues -- they don't reproduce, he
Land has been set aside to protect the woodrat, but even with the protection, its small population and fluctuations make it vulnerable to extinction, McCleery
Conservationists fear those protections won't be enough.
The fish and wildlife service established captive breeding colonies and a release program in 2002 at Tampa's Lowry Park Zoo and at Disney's Animal Kingdom.
When fish and wildlife officers released them, they were much more susceptible to being killed by predators than a normal woodrat.
"In captivity, they can become habituated to people," McCleery
Normally, animals should be scared of people, he
, Jeffrey A. Hostetler, Madan K. Oli.