The Florida panther (Puma concolor coryi) once roamed throughout the southeastern United States, but after years of hunting and habitat destruction the only remaining panthers reside in south Florida. FWC, the U.S. Fish and Wildlife Service, National Parks Service, universities, and other partner organizations work diligently to protect this endangered species.
Approximately 100 to 180 Florida panthers exist today. In 2015, 42 panther deaths were recorded – more than 70 percent of those deaths were vehicle strikes. Shrinking habitat range of Florida panthers is a major concern, but disease also threatens their survival. Since the mid-1980s, scientists have monitored the genetic health of these native cats. Funded by the Florida Panther Trust Fund, FWRI researchers continue to monitor Florida panthers for disease that could cause mortalities, impact their fitness, or impair their reproduction. Currently, researchers are primarily focused on two diseases: the feline leukemia virus (FeLV) and pseudorabies virus (PRV).
Both FeLV and PRV are exotic to the panther population being carried by domestic cats and feral swine respectively. FeLV is the most important infectious disease of domestic cats, and predation of an infected cat by a panther can result in the panther being infected. Once the species barrier is crossed, FeLV can spread panther to panther through fighting, breeding, and other contact. Although some panthers may recover from infection, a large proportion succumb to opportunistic bacterial infections that result from damage to the immune system by the virus. An outbreak occurred in 2003-2004 that resulted in fatal infections in at least five panthers. A vaccination program at that time may have helped end the outbreak. However, since 2010 six more panthers have tested positive for the disease. PRV is also a virus that is new to the panther population. A large proportion of feral swine, which were introduced to Florida in the 1500s, are infected although the virus does not cause significant disease in this species. The virus does pose a threat to the commercial swine industry as well as carnivores (including panthers) and other mammals that come in contact with infected swine. Feral swine are an important prey species for panthers, and consumption of an infected hog that happens to be shedding virus can result in a rapidly fatal infection. Research has shown, using more sensitive diagnostic tests on archived panther tissues, that PRV is having a bigger impact on the panther population than previously estimated; as feral swine populations expand in Florida, the pseudorabies virus could impede expansion of the northern portion of Florida panther habitat.
In the pinelands, swamps, and hammocks of the Big Cypress ecosystem, biologists monitor panthers via radio-collars. The cats are tracked, tranquillized, tested for and vaccinated against FeLV. Uncollared panthers are captured and fitted with radio-collars. When a panther dies, biologists perform a complete necropsy and test for both FeLV and PRV.
FeLV and PRV are the top two infectious diseases causing mortality in Florida panthers; however, management may decrease the risk of both diseases. Keeping domestic cats indoors and vaccinating panthers can prevent FeLV. Managing feral swine is more complicated as the panther depends on this species for food, and the benefits of swine as a prey species may outweigh their risk as a source of pseudorabies. Regardless, managing for a larger white-tailed deer herd, also an important prey species, may reduce the pseudorabies risk. Continued research, monitoring and management is necessary as these diseases continue to be a risk to the endangered Florida panther population, and FWC is collaborating with Colorado State University, UF Department of Wildlife Ecology and Conservation, and others to learn more about the risks of FeLV and PRV to the panther.