Florida Panther Predation Explains White-tailed Deer Decline
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The Florida Panther (Puma concolor coryi) was first considered a subspecies of the North American cougar in the late 19th Century, but a reclassification in 2005 lumped the Florida panther back in with the North American population (Puma concolor couguar)1. Nevertheless, the Florida cougars are the last remaining in the eastern United States and are still referred to as the Florida panther.
The Florida panther was listed as an endangered subspecies under the Endangered Species Preservation Act of 1966, which became the Endangered Species Act in 1973. Their population plummeted between 30 and 50 individuals by the mid-1990s and genetic diversity became a concern for long-term population persistence. Eight females were transplanted into the population from Texas in 1995, which greatly improved population integrity. Subsequently, the Florida panther numbers increased to potentially over 200 individuals by 20152.
Cougars rely on large game as a staple food source, and wild pigs and white-tailed deer are noted as the main prey for Florida panthers, deer being most important when pig populations were low. White-tailed deer are the most popular game animal in Florida, but population declines in recent decades led to reduced sportsman harvest and regulations like antler point restrictions in southern Florida. While the effects of regulation changes had not been evaluated in southern Florida since the 1990s, a similar decline in harvest and hunting effort had been noted. Additionally, deer survival and causes of mortality had not been studied since before the Florida panther population increase following the 1995 translocation of females from Texas.
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Bled et al. (2022)3 hypothesized that “…changes in deer survival would be strongly influenced by the increase in the panther population…”, and they “…predicted an increase in panther predation rates and a decrease in deer survival relative to studies conducted prior to genetic restoration of Florida panther.” To test their hypothesis, they collared and GPS-tracked 241 deer across the Florida Panther National Wildlife Refuge and Big Cypress National Preserve from January 20-15 to December 2018 to determine survival rates and fate of those that died during the study.
Overall, 55.6 percent (134) of collared deer died and 43.6 percent (105) survived with 0.8 percent (2) unaccounted for at the conclusion of the study. Florida panthers accounted for unequivocally higher predation at nearly 40 percent compared to all other predation sources being less than 3 percent. Statical modeling drew panther predation correlations to deer sex and other environmental variables.
Doe predation risk increased during fawning season when bucks experienced relatively low predation. Bucks experienced higher predation during rut, and overall higher mortality from predation and other variables across the study compared to does.
The authors concluded that “Panther predation [on white-tailed deer] increased substantially from the period before panther genetic restoration efforts (1995) and the associated increases in panther abundance.” While other environmental variables play a role in southern Florida white-tailed deer survival, the Florida panther as an apex predator significantly influences overall population trends.
1 Wozencraft, W. C. (2005). “Subspecies Puma concolor couguar“. In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 544–545. ISBN 978-0-8018-8221-0. OCLC 62265494
2 Florida Fish and Wildlife Conservation Commission. (2018). Annual report on the research and management of Florida panthers: 2017–2018. Fish and Wildlife Research Institute and Division of Habitat and Species Conservation.
3 Balancing carnivore conservation and sustainable hunting of a key prey species: A case study on the Florida panther and white‐tailed deer – Journal of Applied Ecology