By Dennis B. Jordan

The Florida panther (Felis concolor coryi), like most other endangered species, is threatened by a number of problems. Habitat loss or fragmentation, environmental contaminants, automobile collisions, reduced prey availability, and human disturbance have all taken a toll. Many scientists also believe that the panther likely suffers from a compromised immune system. But perhaps the most serious threat to the Florida panther is that of genetic viability.

Reduced to a single population of 30-50 adults, the Florida panther has been isolated from genetic interchange with other populations for a century or longer. Biologists believe that close inbreeding and erosion of the gene pool account for such medical problems as reduced fertility, cardiac abnormalities, and infectious diseases in the Florida panther population.

The Fish and Wildlife Service (FWS) approved the first recovery plan for this severely endangered animal in 1981. That same year, the Florida Game and Fresh Water Fish Commission launched a radio-tracking effort with FWS funding. Panther recovery activities initially were directed toward 1) protecting and enhancing the remaining animals and habitats and 2) research on biological, demographic, and genetic data needed to carry out the recovery program. A significant boost in the recovery effort came in 1986 with formation of the Florida Panther Interagency Committee, which coordinates recovery activities among the various Federal and State agencies cooperating in the effort. The recovery plan was revised in 1987 and again in early 1995 to incorporate genetic restoration as part of the recovery program.

By early 1989, biologists had captured and radio-collared 29 panthers, enough to provide the data needed for a population viability analysis. That year, at a 1989 workshop sponsored by the FWS, computer-modeled demographic projections indicated that 1) the panther population was continuing to decline, 2) the population was losing genetic diversity at a rate of 3-7 percent each generation, 3) genetic diversity would continue to erode even if the population was stabilized, and 4) a reduction in fitness may have already occurred as reflected in the high incidence of infertility. The conclusion was that, under existing demographic and genetic conditions, the Florida panther would likely become extinct in 25-40 years.

Four subsequent workshops evaluated additional data on population viability and potential strategies to prevent the panther's extinction. The initial plan called for establishing a large captive-breeding population to produce animals for release into the wild. As a start, biologists removed six panther kittens from the wild in 1991 and another four in 1992.

From 1989 to mid-1992, biologists captured and examined more than 75 wild panthers (including 23 that were radio-tracked), gaining a great deal of additional information on panther health, reproduction, mortality, and genetics. These data confirmed that the population's health continued to deteriorate significantly.

In response, the participating agencies convened another workshop in October 1992 to reevaluate options for ensuring the panther's survival. They decided to cease the removal of panther kittens from the wild and put the captive breeding program on hold. Data presented at the workshop indicated that aggressive action to restore genetic viability could be the only way to save the Florida panther.

Biologists at the workshop considered various options for restoring genetic health to the Florida panther. The strategy eventually recommended by workshop participants, and accepted by the Interagency Committee, was to restore the flow of genetic material into the Florida population that would have occurred naturally if human impacts on the environment had not resulted in its isolation. The decision was to introduce genetic material from the closest remaining F. concolor population that historically overlapped the range of the Florida panther--the Texas subspecies (F. c. stanleyana).

Biologists at the 1992 workshop decided that the introduction of 6 to 10 new breeding females was needed to reverse the effects of inbreeding and genetic loss in the Florida panther population. The participants also concluded that this would not swamp the existing gene pool, which may be adapted to local environmental conditions. A workshop in September 1994 put together a detailed plan for genetic restoration and management of the Florida panther. The FWS also produced an environmental assessment on the restoration program and various alternatives.

The genetic restoration effort for the Florida panther began in 1995 with the translocation of eight females from the Texas population into the Florida population. Two of these panthers were released into the 70,000-acre (28,300-hectare) Fakahatchee Strand State Preserve in central Collier County, four went to various units of the 600,000-acre (243,000-ha) Big Cypress National Preserve, and the final two were placed into the Long Pine Key area of Everglades National Park (Note sidebar).

State and Federal biologists will monitor the F.c. stanleyana females and their offspring closely to determine if they promote fertility, genetic diversity, and overall health in the Florida panther population. Although it is too soon to know if the program will succeed, the outlook for the Florida panther appears brighter today than at any time in recent history.

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Sidebar:The introduced panthers seem to have adapted to their new homes. Two intercross litters have been produced as of early 1996. The first litter, born in the Big Cypress National Preserve at the end of September 1995, contained one kitten of each sex. The sire is an uncollared male Florida panther. The second litter, consisting of a single female kitten, was born at the end of November. It was produced by one of the females released into the Fakahatchee Strand State Preserve and a collared male (known to biologists as #51). All young have been marked with transponders and will be radio-collared at 6 months of age. Another adult female released in the Big Cypress Reserve was struck by a vehicle and killed in September 1995 while crossing a road in Hendry County. A necropsy revealed that she was carrying three fetuses.