Forest cover mediates large and medium-sized mammal occurrence in a critical link of the Mesoamerican Biological Corridor.

Connectivity of natural areas through biological corridors is essential for ecosystem resilience and biodiversity conservation. However, robust assessments of biodiversity in corridor areas are often hindered by logistical constraints and the statistical challenges of modeling data from multiple species. Herein, we used a hierarchical community occupancy model in a Bayesian framework to evaluate the status of medium and large-sized mammals in a critical link of the Mesoamerican Biological Corridor (MBC) in Costa Rica. We used camera traps deployed from 2013-2017 to detect 18 medium (1-15 kg) and 6 large (>15 kg) mammal species in a portion of two Jaguar Conservation Units (JCUs) and the Corridor linking them. Camera traps operated for 16,904 trap nights across 209 stations, covering an area of 880 km2. Forest cover was the most important driver of medium and large-sized mammal habitat use, with forest specialists such as jaguars (Panthera onca) and pumas (Puma concolor) strongly associated with high forest cover, while habitat generalists such as coyotes (Canis latrans) and raccoons (Procyon lotor) were associated with low forest cover. Medium and large-sized mammal species richness was lower in the Corridor area ([Formula: see text] = 9.78±1.84) than in the portions evaluated of the two JCUs ([Formula: see text] = 11.50±1.52). Puma and jaguar habitat use probabilities were strongly correlated with large prey species richness (jaguar, r = 0.59, p<0.001; puma, r = 0.72, p<0.001), and correlated to a lesser extent with medium prey species richness (jaguar, r = 0.36, p = 0.003; puma, r = 0.23, p = 0.064). Low estimated jaguar habitat use probability in one JCU (Central Volcanic Cordillera: [Formula: see text] = 0.15±0.11) suggests that this is not the jaguar stronghold previously assumed. In addition, the western half of the Corridor has low richness of large mammals, making it necessary to take urgent actions to secure habitat connectivity for mammal populations.