Abundance, species richness and energy availability in the North American avifauna

To determine how species richness, abundance, biomass, energy use and mean number of individuals per species scale with environmental energy availability in wintering and breeding avian assemblages, and to contrast assemblages of (i) common and rare species and (ii) breeding residents and migrants. To assess whether such patterns are compatible with the ‘more individuals hypothesis’ (MIH) that high-energy areas are species-rich because they support larger populations that are buffered against extinction.