Demography and population dynamics of the Florida panthers: An integrated population modeling approach

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Brandon D. Merriell, School of Natural Resources & Environment, University of Florida, Gainesville, FL, David P. Onorato, Florida Fish and Wildlife Conservation Commission, FL, Jeffrey A. Hostetler, US Fish and Wildlife Service, Madelon van de Kerk, Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT and Madan K. Oli, Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL

Background/Question/Methods
Estimating population parameters for rare and endangered species is often challenging due to small sample sizes, which can lead to low levels of precision. One way to improve precision is to integrate varied sources of data within one analytical framework, such that information is shared across parameters and data types, thereby improving precision of all estimated parameters. We modeled population dynamics and estimated vital rates of the endangered Florida panther (Puma concolor coryi) within an integrated population modeling (IPM) framework incorporating multiple data sets (live recapture, dead recoveries, radio-telemetry, den check data and two population abundance indices) that collectively spanned >30 years of research. Our model included both demographic and environmental stochasticity, as well as density-dependence in kitten survival. We implemented the IPM in a Bayesian analytical framework using NIMBLE in the R computing platform.
Results/Conclusions
Survival of Florida panthers was strongly sex- and stage-specific, with kittens having the lowest survival probability of 0.32 (95% CRI: 0.22 – 0.43). Subadults had the highest survival among females, while prime adults had the highest survival among males, with survival probabilities of 0.95 (0.90 – 0.98) and 0.75 (0.67 – 0.82), respectively. Across all stage classes, females consistently had higher survival than their male counterparts. Both breeding probability and average litter size were also stage-specific. Breeding probabilities ranged from 0.25 (0.14 – 0.37) for old adults to 0.55 (0.49 – 0.61) for prime adults, while average litter sizes ranged from 2.29 (1.68 – 2.96) for old adults to 2.95 (2.50 – 3.43) for subadults. Across our study period, the mean annual population growth rate was 1.06 (1.04 – 1.10). Our estimates of Florida panther demographic parameters were more precise than previous estimates based on single data types, highlighting the advantage of using the IPM framework. Additionally, owing to the flexibility of IPMs, our study is the first to incorporate two different indices of Florida panther abundance within a single analysis, eliminating the need to arbitrarily choose one index over the other or conducting the same analysis twice.