The relationship between habitat breadth, habitat position, and abundance in forest and woodland birds along a continental gradient

Multivariate analyses of habitat ordinations (nonmetric, multidimensional scaling) were used to characterise the habitat breadth (β) and habitat position (γ) of 92 species of forest and woodland birds along a 250 km transect in SE Australia. Abundances were estimated on the basis of excluding zero-density sites (absence), leading to the notion of average density at sites at which a species occurs. There was a significant inverse correlation between β and γ. This result, when used in conjunction with the distributions of β and γ, proved incompatible with existing models of habitat occupancy patterns. The correlation between β and average density, and between γ and average density, each was approximately zero, results that differed from the findings of other studies at the range-level geographic scale. These differences are interpreted in light of the insensitivity of range-based studies, which do not explicitly account for habitat structure, to the geographic distributions of preferred habitat types of individual species of animals