You can’t run but you can hide: the negative influence of human presence on mid-sized mammals on an Atlantic island

Abstract

Here, we report the results of a camera-trapping survey of mid-sized (1–50 kg) mammals on an oceanic Atlantic forest island in Brazil. Despite 80% of the island being formally reserved for conservation, the island’s northern areas support a small, but rapidly growing human population that we expected would disturb the mammals and their foraging and movement behaviors. Hunting activities are also more frequent and severe on the north side of the island, closer to the villages. We tested the following hypothesis: the probability of occupancy, detectability, and abundance of mid-sized mammals will be higher in less-disturbed areas on southern parts of the island than in more-disturbed areas to the north. Ordination using multi-dimensional scaling (MDS) highlighted that mammal assemblages were differentiated between the northern and southern slope areas, and regression analyses showed MDS scores to be associated strongly with an index of human population density. Occupancy models for Didelphis aurita, Dasypus novemcinctus, Dasyprocta leporina, and Cuniculus paca showed no effect of habitat covariates, but there were marked effects of human activity impact on the detection probability of all species, except D. aurita. Species detections and local abundances were higher in the less disturbed southern parts of the island. Our results support the notion that mid-sized mammals will change their movement and foraging behaviors as a function of human activities, even inside reserved, protected areas.