DOI: 10.5061/dryad.m63xsj40d
title: Mammal population densities at a global scale are higher in human-modified areas

description: Global landscapes are changing due to human activities with consequences
 for both biodiversity and ecosystems. For single species, terrestrial
 mammal population densities have shown mixed responses to human pressure,
 with both increasing and decreasing densities reported in the literature.
 How the impacts of human activities on mammal populations translates into
 altered global density patterns remains unclear. Here we aim to
 disentangle the effect of human impacts on large-scale patterns of mammal
 population densities using a global dataset of 6729 population density
 estimates for 468 mammal species (representing 59% and 44% of mammalian
 orders and families). We fitted a mixed effect model to explain the
 variation in density based on a 1-degree resolution as a function of the
 Human Footprint Index (HFI), a global proxy of direct and indirect human
 disturbances, while accounting for body mass, trophic level and primary
 productivity (Normalized Vegetation Index; NDVI). We found a significant
 positive relationship between population density and HFI, where population
 densities were higher in areas with a higher HFI (e.g., agricultural or
 suburban areas – no populations were located in very high HFI urban areas)
 compared to areas with a low HFI (e.g., wilderness areas). We also tested
 the effect of the individual components of the HFI and still found a
 consistent positive effect. The relationships remained positive even
 across populations of the same species, although variability among species
 was high. Our results indicate shifts in mammal population densities in
 human modified landscapes, which is due to the combined effect of species
 filtering, increased resources, and a possible reduction in competition
 and predation. Our study provides further evidence that macroecological
 patterns are being altered by human activities, where some species will
 benefit from these activities, while others will be negatively impacted or
 even extirpated.
description: This data file includes 6729 population density estimates of 468
 terrestrial mammal species. Population density is measured as the number
 of individuals per square kilometre. Also included are taxonomic
 information (order & family), longitude/latitude of the location
 where population density was estimated, the site/country/continent where
 the estimate was collected, the method used to estimate density, mean body
 mass (grams), and trophic guild. The environmental covariates associated
 with each denisty estimate is also included accessibility, human footprint
 index, night-time lights, percentage of cropland, percentage of pasture,
 human population density, Normalized Difference Vegetation Index (NDVI)
 and mean mammal species richness.  These environmental covariates have
 three different spatial resolutions including 1 km, 10 km and 50 km, and
 were extracted based on the longitude/latitude position and in the case of
 the 10 km data, using a buffer with a radius equal to the density value
 mulitplied by 100. Please see the associated manuscript and supplementary
 materials for details on the data sources and calculation
 methods.