Global Patterns of Animal Abundance and Species Energy Use

There is enormous variation among animal species in population density and population energy use. Density (D) is known to vary strongly with body weight (W), while allometric scaling of population energy use is disputed. The present study examines this variability in reported species densities and energy consumption to test the hypothesis that the patterns are related to environmental energy levels and to the efficiency of energy utilization. We found that the intercepts, but not slopes, of density-body size relationships of the form log D = a + b log W differ significantly among broad groups: invertebrates, vertebrate ectotherms, mammals and birds