Fig. 2.

Taxonomically nested analysis of variance (order, family, genus, species) in measures of geographic range, habitat breadth, and relative abundance. Data refer to 3,033 species of nonraptorial land birds of South America and are from Stotz et al. (72), who reported the number of zoological regions (of 22) and number of forested (of 14) and open (of 14) habitats occupied by each species. Abundance was assigned to one of four ordinal categories (rare, fairly common, common, or abundant). Habitat stratum was assigned to one of five ordinal categories (ground, understory, midcanopy, canopy, or aerial).