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Mammal population densities at a global scale are higher in human-modified areas

Citation

Tucker, Marlee A.; Santini, Luca; Carbone, Chris; Mueller, Thomas (2020), Mammal population densities at a global scale are higher in human-modified areas, Dryad, Dataset, https://doi.org/10.5061/dryad.m63xsj40d

Abstract

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.

Usage Notes

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.

Funding

Robert Bosch Stiftung

Goethe International Postdoctoral Program, Award: FP7/2007–2013 Under REA Grant #291776

Radboud Excellence Initiative Fellowship

Goethe International Postdoctoral Program, Award: FP7/2007–2013 Under REA Grant #291776

Radboud Excellence Initiative Fellowship