Figure 1.

Sources of extinction risk among threatened birds. (A) Relative proportion of species in database threatened by each source of extinction. Data are individual threatened species. “Other” sources of extinction risk include competition, hybridization, and disease. (B) Association between proportion of species in each family threatened by habitat loss only versus proportion of species in each family threatened by persecution/introduced predators only; the heavy black line shows the results of regression model restricted to only those families that contain threatened species (61 families: F = 23.35, df = 1, 59, P < 0.0001; (proportion of family threatened by habitat loss only) = [0.42–0.49 × (proportion of family threatened by persecution/predation only)^1/2]². Data are raw family-typical values.