Balancing carnivore conservation and sustainable hunting of a key prey species: A case study on the Florida panther and white‐tailed deer

Abstract

Large carnivore restoration programs are often promoted as capable of providing ecosystem services. However, these programs rarely measure effects of successful restoration on other economically and ecologically important species. In South Florida, while the endangered Florida panther Puma concolor coryi population has increased in recent years due to conservation efforts, the population of its main prey, the white‐tailed deer Odocoileus virginianus, has declined in some regions. The extent to which panther predation has affected deer populations has been difficult to assess because several other factors have changed during this period, including hydrology and hunting regulations. We collected known‐fate survival data on 241 GPS‐collared adult deer (156 females and 85 males) from 2015 to 2018 in the Florida Panther National Wildlife Refuge and the Big Cypress National Preserve in Florida, USA, to assess effects of panther predation on the deer population, while also evaluating the impacts of hunting and hydrology. Predation was the primary cause of death (110 of 134 mortalities), and 87% of predation events were attributed to panthers, a much greater rate than reported by studies conducted before the panther genetic restoration effort initiated in 1995. One deer was legally harvested, and two were likely killed by poachers. Increasing water depth decreased female survival but had little impact on male survival, and drowning was never a cause of mortality. Females had greater survival probability than males, except during fawning season. From 2015 to 2018, annual survival rates increased from 0.61 (0.52–0.70) to 0.86 (0.79–0.91) for females, and from 0.45 (95% CI: 0.33–0.58) to 0.79 (0.69–0.86) for males. Synthesis and applications. High predation rates, coupled with previous evidence of low recruitment of deer in South Florida, suggest that it will be challenging to meet society's competing demands for large predator restoration and sustainable deer harvest. Deer hunting in the area must remain tightly controlled, for now, if it is to be sustainable, and managers should seek to mitigate effects of high waters and improve deer habitat quality to increase deer population viability. Future work should closely monitor the deer population to assess if management actions can increase vital rates and abundance in the context of high predation rates.

Noninvasive camera data and spatial capture–recapture models reveal strong temporal variation in fawn survival

“…Using that fecundity rate, our survival estimate of 36% in 2015 would equate to an expected fawn recruitment rate of 43.2% (1.2 × 36%), which may be high enough to replace adult losses in the population (Chitwood, Lashley, Kilgo, Moorman, et al, 2015; Peters et al, 2020). However, our estimate of 13% fawn survival in 2016 translates to a recruitment rate of 15.5%, which is unsustainable for population persistence in the presence of high adult mortality (Bled et al, 2022).…”

“…Our observed fawn survival and recruitment estimates suggest that extreme weather events can cause strong temporal variation in demography. Consistently low fawn survival over multiple years, when paired with low adult survival, may be a cause for concern for the viability of deer in the Big Cypress Basin (Bled et al, 2022). Additional sources of fawn mortality, such as the expansion of Burmese pythons into the northern Big Cypress Basin and ongoing hydrologic shifts driven by climate change, may continue to reduce neonate survival and influence other demographic parameters in this system.…”

“…Meanwhile, the Florida panther ( Puma concolor coryi ) population increased from 20–30 individuals in the early 1990s to 120–230 twenty years later (FWC, 2017; Johnson et al, 2010). Florida panther predation is the largest source of mortality for adult deer within the panther's range (Bled et al, 2022), and the adult deer survival rate is lower than it was in the 1990s (Bled et al, 2022; Land, 1991). Although adult female survival is often the most influential vital rate in deer population growth, low fawn recruitment can further constrain growth in low‐density herds (Chitwood, Lashley, Kilgo, Moorman, et al, 2015), such as those of south Florida.…”

Rain, recreation and risk: Human activity and ecological disturbance create seasonal risk landscapes for the prey of an ambush predator

“…or nocturnal (sunset to sunrise) categories using the maptools package (version 1.1-5; Bivand & Lewin-Koh, 2018). Next, we calculated the upper (≥66% distribution), median (<66% and >34% distribution)…”

“…Human activity has the potential to induce both spatial and temporal antipredator responses by deer to panthers and humans (Figure 2a). However, considering competing risks, deer are likely to perceive panthers as the greater threat, as human hunting efforts are limited (0.01% total deer mortalities) and restricted to antlered males during the flooded season, whereas panther predation risk remains substantially higher for both sexes, particularly for females, year‐round (72% total deer mortalities; Bled et al, 2022; Florida Wildlife Code, 68A‐13.004). Consequently, deer may exhibit temporal antipredator responses by increasing their diurnal activity to coincide with periods when panthers are less active.…”