Understanding the niche requirements of species is the foundation to predict the fate of biodiversity in face of climate change. However, the characterization of species’ niche is entangled with the spatial scale at which environmental data is analyzed. We hypothesized that the spatial scaling relationship of species’ environmental niche is mainly affected by species’ range size, dietary niche breadth and environmental heterogeneity. To test our hypotheses, we used eBird occurrence data to analyze the scaling relationship of environmental niche breadth of 260 birds in the Western Hemisphere. We used the determinant of the covariance matrix (e.g. generalized variance) of environmental variables as a measure of niche breadth, which could be decomposed into the variances of univariate variance and a correlation component. We correlated each niche breadth component with species’ range size, dietary niche breadth, body mass, centroid longitude and latitude of species’ range, and environmental heterogeneity.
Results/Conclusions
Our results show that range size is the dominant factor that influences the spatial scaling of environmental niche in birds. Other factors include dietary niche breadth, centroid latitude and longitude of species range, spatial heterogeneity of environmental variables. Different niche breadth component responds differently to these factors. Our results suggest that the niche breadth of tropical and small-range species are more sensitive to the choice of spatial scale than temperate and large-range species.