Anthropogenic effects on the occurrence of medium-sized mammals on the Brazilian Pampa biome

The Pampa biome within Brazil is one of South America’s most endangered biomes, due to conversion to croplands and use for cattle farming, with very limited coverage by protected areas. We investigated the impacts of (i) human population density, (ii) grassland and (iii) forest cover, (iv) protected areas and (v) mean size of farms on the occurrence patterns of 18 medium-sized mammal species. We gathered information on the occurrence of these species between 2001 and 2010 from the literature and using unpublished field data from local experts. We obtained 1066 records, varying between 13 and 101 per species. Grassland cover had consistently positive effects on species richness (considering the 18 analyzed species), endangered species (considering 10 species that are endangered or data deficient) and occurrence of five individual species (considering each species separately). Human population density, forest cover and mean size of farms had diverse effects on individual species; however, both forest cover and human population density had positive effects on species richness and endangered species occurrence. For human population density this may result from areas suitable for people being similar to those suitable for many native species. The protected area network of the Pampa biome appeared ineffective at protecting the focal species, with predominantly negative effects on mammal occurrence. This inefficiency is probably related to its minor coverage; only 2.9% of the biome area is under any level of protection and only 0.4% under strict protection. To guarantee the conservation of mammal species in this threatened biome, it is important to protect the last remnants of native vegetation, mainly grasslands, avoiding their conversion into croplands.