KEY LARGO -- Survival of the endangered Key Largo woodrat cannot be helped by captive breeding programs with limited release areas, according to a study published this month by a University of Florida biologist.
The eight-page report, featured in Biological Conservation, outlined the past failures of captive breeding and release programs for the diminutive hardwood hammock denizen teetering on the brink of extinction.
Among its recommendations, the study says any future program must vary the location of releases, though the availablility of hardwood hammocks has dwindled over the years in the Florida Keys due to development.
"You can't release them all in one place," said Robert McCleery, a biologist who co-authored the study.
Part of the rodent's important role in the ecosystem is seed dispersal, which creates more brush and trees. The rodent also serves as prey for other native species, including birds and snakes. In 1984, federal conservation officers placed the Key Largo woodrat on the endangered species list. Its primary habitat is now limited to federal and state protected lands in North Key Largo.
"This was a modeling exercise," McCleery explained. "We took data already out there and conducted an autopsy."
The biologist said the study is intended to help guide wildlife officials in the future when deciding on whether to start a new program.
In early 2012, Disney's Animal Kingdom, in partnership with Lowry Park Zoo in Tampa and U.S. Fish and Wildlife Service, discontinued its captive breeding and release program after three failed efforts in North Key Largo.
A sensitive issue that McCleery declined to address is the role feral cat populations have played in eliminating the woodrat.
Jeremy Dixon, a biologist who manages Crocodile Lake National Wildlife Refuge, which is home to most of the remaining wild Key Largo woodrats, said the matter warrants discussion. He says captive breeding and release programs will fail as long as feral cats roam the refuge.
"The community needs to decide if they want feral cats or endangered species," Dixon said.
January marks the second year in a three-year study of the native rodents. The study, funded through a $150,000 grant from the U.S. Fish and Wildlife Service, hopes to determine the usefulness of manmade shelters for the woodrats. The study, which is performed in partnership with North Carolina State University, also seeks to analyze the success of a trap-and-shelter program in the refuge for feral cats.
Dixon said the refuge is not looking to restart a breeding program but to manage the non-native predators the rodents face. He hopes the removal of cats will help the current woodrat population.
"They can't survive when there's cats in there," Dixon said. "Without the cats, we would be talking more about recovery than preventing extinction. ... The issue is always going to be getting the community behind keeping cats off the refuge."