Estimate of Agouti (Dasyprocta sp.) Abundance in the Emílio Goeldi Zoobotanical Park

Many modern urban parks have free-ranging animals. This helps with the ex situ conservation of species and raises empathy and awareness. However, these populations, which receive food and medical treatment, can exceed expected densities and require management. Estimating population size is the first step. In this study, we used the capture–marking–recapture method to estimate the population size of free-ranging Dasyprocta sp. at the Emílio Goeldi Zoobotanical Park. Captures were conducted between October 2024 and December 2025. Each individual was weighed, measured, sexed and microchipped. We estimated population size using the Rcapture package and selected the best-fitting model using the Akaike information criterion (AIC). Size structure data showed that only two young animals were captured, and medical data recorded only two deaths during the study period. Due to closure, high population density and low birth and death proportions, we used closed population models. A total of 123 captures were made, including 94 markings and 28 recaptures. The estimated population size was 201 individuals, corresponding to a density of 37.2 ind/ha. This greatly exceeds previously reported densities for agoutis, and suggests an ecological imbalance in the study area. These findings provide an important baseline for monitoring and managing this population.