Beach mice are small nocturnal rodents who spend daylight hours in burrows they create in sand dunes and are dependent on undisturbed beaches for their survival. Because of habitat loss and mortality from feral animals, Perdido Key beach mice (PKBM) were declared an endangered species in 1983. The beach mouse population at Perdido Key, a small strip of land that straddles the Alabama-Florida border, was nearly wiped out in the mid-1990's when hurricanes Erin and Opal ravaged Perdido Key’s beaches. In September 2004, as Hurricane Ivan was approaching the Florida-Alabama coast, staff from the Florida Wildlife Commission (FWC) removed eight PKBM from the wild, including a pregnant female. These animals became the founders of the current captive population in the event that wild mice disappeared altogether. In the past, mice populations have declined following strong hurricanes to as few as a few dozen individuals, but now the population is believed to exceed 1,000 animals, thanks in part to the release of captive mice born from zoos. While individual populations appear to be growing, the Perdido Key beach mouse will probably never make it off the endangered species list because of continued habitat loss, predation by feral animals and because their natural habitat is subject to occasional catastrophic storms.
The Palm Beach Zoo became involved with these endangered mice in 2007 when a captive zoo breeding program was established in the hopes of one day being able to reintroduce PKBM to their natural habitat. This collaboration currently involves the Palm Beach Zoo & Conservation Society, Brevard Zoo in Melbourne, and the Santa Fe Teaching Zoo in Gainesville, as well as the FWC, The US Fish and Wildlife Service, the Florida State Parks Service, and the Alabama Fish and Game. In October of 2009, the Palm Beach Zoo’s first offspring were confirmed. In the months that have followed, seven out of the zoo’s nine breeding pairs have successfully reproduced with over 80 offspring reaching maturity.
On March 27, 2010, staff from the zoo’s animal care and research departments traveled to Perdido Key with 16 of the offspring to take part in the first ever release of captive PKBM into the wild. Personnel from USFWS, FWC, Brevard Zoo, Santa Fe Teaching Zoo, independent researchers, and the Palm Beach Zoo worked together to individually mark each mice using small metal ear tags and placed radio collars on more than half of the mice being released. Once all mice were individually identified, they were transported to the release site, just over the Alabama border on Perdido Key. Mice from Brevard Zoo and Palm Beach Zoo were release in even ratios in three separate sites each containing four release pens.
The mice’s movements were tracked for two weeks after release using radio collars. Regular trapping of the mice continued to provide us with information on how the population wass both moving and growing. Three months after being released, a number of the females were found to be pregnant and over a dozen offspring were also identified. The mice were also found in areas of Perdido Key where the species has not been seen in over a decade, strong evidence that this new population is thriving.
Six months after the initial release, Palm Beach Zoo staff assisted with setting and checking close to 400 traps for two nights to assess current population numbers and distribution. The population has tripled and continues to grow as five of the trapped mice were pregnant females, including several second wild generation individuals. The mice have spread out evenly over their range and no ill effects have been seen thus far from the oil spill in the Gulf. The Palm Beach Zoo will continue their captive breeding efforts in conjunction with other Florida AZA institutions and will coordinate with the USFWS and FWC on future releases.
This is the first reintroduction program of captive PKBM to be implemented and Palm Beach Zoo staff members are proud to be able to take part in this important work.