Combined effects of land use and hunting on distributions of tropical mammals

Land use and hunting are 2 major pressures on biodiversity in the tropics. Yet, their combined impacts have not been systematically quantified at a large scale. We estimated the effects of both pressures on the distributions of 1,884 tropical mammal species by integrating detailed land-use maps (1992 and 2015), species-specific habitat preference data, and a hunting-pressure model. We further identified areas where the combined impacts were greatest (hotspots) and least (coolspots) to determine priority areas for mitigation or prevention of the pressures. Land use was the main driver of reduced distribution of all mammal species considered. Yet, hunting pressure caused additional reductions in large-bodied species' distributions. Together, land use and hunting reduced distributions of species by 41% (SD 30) on average (year 2015) with a small overlap between pressures of only 2% on average. Land use contributed more to the loss distribution (39% on average) than hunting (4% on average). However, hunting reduced the distribution of large mammals by 29% on average; hence, large mammals lost disproportional amount of area due to the combination of pressures. Gran Chaco, the Atlantic Forest, and Thailand had high levels of these combined pressures (hotspots of area loss). In contrast, the Amazon and Congo basin, the Guianas, and Borneo had relatively low levels (coolspots of area loss) of combined pressures. Overall, hunting and human land use increased from 1992 to 2015. Losses in distribution increased from 38% to 41% on average across the species. To effectively protect tropical mammals, conservation policies should address both pressures simultaneously because their effects are highly complementary. Our spatially detailed and species-specific results may support future national and global conservation agendas, including the design of post-2020 protected-area targets and strategies.