Don’t shoot! How poaching may affect richness, biomass, and occupancy of non-volant mammals in an Atlantic Forest protected area, Brazil

Abstract Hunting in tropical forests provides nutrition and financial income for local communities and is deeply rooted in social and cultural traditions. On the other hand, this activity, by locally reducing or extirpating populations of game species, may be responsible for the degradation and loss of key forest maintenance services. In Brazil, hunting is illegal (hereafter referred to as poaching). We evaluated, by accounting for imperfect detectability, the effects caused by poaching on mammals in the Vale Natural Reserve. We collected data over 5-years (between 2013 to 2018) using line-transect and camera-trapping to evaluate poaching effects on the density, biomass, richness, and site occupancy of mammalian species. Our complete data set included a total survey effort of 32,175 camera days across five camera trap surveys (825 working days), with a total of 25,254 records of 27 non-volant mammals. We found a negative effect of poaching index on overall-species richness based on our multi-species occupancy model. The greatest reduction in biomass occurred for ungulates and armadillos. Our results suggest that poaching can have large consequences for biodiversity in one of Brazil's largest Atlantic Forest remnants. Ours is the first study in the Atlantic Forest estimating the medium-term poaching impact on mammalian populations, demonstrating a potentially negative effect on density, biomass, and occupancy of species which are of importance for local ecosystem functioning. We demonstrate the need to start monitoring other populations of vertebrates that are a target to poaching, not only in the Atlantic Forest but in other Neotropical ecosystems.