Human Population Density and Growth Validated as Extinction Threats to Mammal and Bird Species

Abstract

Predictions of extinction threats for mammal and bird species in 2010, on the basis of projections from the 2000 model, were strongly correlated with the observed data. A regression of the predicted on the observed threatened species was statistically significant (r2=83.8 %, p<0.001, n=114), based upon the variables of human population density and species richness alone. The model was slightly improved by accounting for the density of endemic mammals (r2=85.2 %, p<0.001, n=114) (Fig. 1). Visual inspection of plots of the residuals revealed that they were normally distributed, fell within the 95 % confidence interval, and showed no patterning against the predicted outcomes.