Density, habitat use and activity patterns of the last giant armadillo population in the Brazilian Atlantic Forest

Abstract

Basic data on the biology and ecology of the giant armadillo (Priodontes maximus) from the Atlantic Forest are practically non-existent. Information on population density and habitat use is vital to assess the long-term population viability and to design effective management and conservation strategies for the Atlantic Forest’s last population of the species. In this study, we estimated density and abundance, evaluated the influence of habitat features and human-altered habitats on the occupancy and detection probabilities of giant armadillos and investigated their activity patterns. Our study was conducted in a forested protected area, the Rio Doce State Park (RDSP) that represents one of the largest continuous remnants of Atlantic Forest in Brazil. We used a random survey design with a blocking arrangement of sampling units and found an estimate of 60.7 individuals (95% CI 26.8–94.6) with a density of 10.67 individuals/100 km² (95% CI 5.28–18.65). From the model-averaged estimates, occupancy probability ($\widehat{\Psi }$) = 0.68 (95% CI 0.18–0.95), and detection probability ($\widehat{p}$) = 0.07 (95% CI 0.00–0.14). The occupancy probability was strongly associated with greater distances from lakes (w₊ = 0.58), while the detection probability was strongly associated with a greater number of days in which the camera traps remained operating (w₊ = 0.63), higher terrain slope (w₊ = 0.61), and greater distances from the cities (w₊ = 0.56). Giant armadillos across sexes were more active during the night (93.5% of the records), with activity peaks before midnight and before sunrise. Giant armadillos presented moderate activity overlap with jaguars ($\widehat{{\Delta }_{1}}$ < 0.54) and low with pumas ($\widehat{{\Delta }_{1}}$ < 0.36). Our work is the first attempt to study the ecology of giant armadillos in the Atlantic Forest. Our findings of a well-established population of giant armadillos in RDSP are extremely important to guide future studies and conservation actions for the species in this biome. We also highlight the potential conservation value of a protected area such as the RDSP in a human-dominated landscape as one of the last strongholds for giant armadillos in the Atlantic Forest.