Community organization in hummingbirds: relationships between morphology and ecology.

Abstract

Temperate North American hummingbirds are convergent: more similar in bill length, body weight, and wing length than predicted by several null models. These species also are more similar to each other than they are to more closely related (congeneric) species from subtropical and tropical habitats. Hummingbirds of the Greater and Lesser Antilles show a nonrandom distribution of species among islands: all islands inhabited by hummingbirds have at least 2 species, and these fall into 2 distinctly different size categories. Bill length increases more rapidly with increasing body weight in West Indian hummingbirds than in random samples of hummingbirds of the world or in other birds. These morphological patterns appear to reflect interspecific competition among hummingbirds and mutualistic coevolution with flowers. Hummingbird species of similar morphology use similar floral resources but rarely coexist in the same local areas. Species of divergent morphology exploit different food resources and frequently coexist locally. Length of the bill, which influences access to different kinds of flowers, is particularly important in the organization of these simple hummingbird associations. -from Authors