Jaguar (Panthera onca) population dynamics in an “isolated” national park in the Cerrado biome, Brazil

Abstract

The jaguar (Panthera onca) is endangered throughout its geographical distribution, yet assessments of jaguar population dynamics are scarce. This study uses camera trap data from 4 surveys spanning 8 years to gain knowledge on jaguar population dynamics in Emas National Park (ENP), one of the largest protected areas in the Brazilian Cerrado biome, surrounded by large scale agriculture. We used spatially explicit capture-recapture models (SCR) to estimate jaguar density and population trends, and Cormack-Jolly Seber models (CJS) to estimate apparent survival. We derived estimates of recruitment into the independent population (adult and subadult) from population trends and survival estimates. Baseline detection rates were negatively affected by distance to river, higher for males than females, and on-road than off-road. The movement parameter σ was higher for males than females. Sex-ratio was slightly skewed towards females, and survey specific density estimates ranged from 0.14 (95% CI = 0.07 – 0.30) to 0.25 (95% CI = 0.13 – 0.46) ind./100km², leading to an average annual population growth rate of 0.94 (95% CI = 0.82 – 1.06), i.e., a largely stable population. Survival was high (0.77; 95% CI = 0.57 – 0.89), and some individuals remained in the population for over 10 years, pointing towards a healthy population with low turn-over rates. However, recruitment into the independent population was low (0.19; 95% CI = 0.02 – 0.40), suggesting a somewhat isolated and saturated population. Our results highlight the importance of further conservation strategies to prevent population decline from anthropogenic pressures and stochastic factors.