Community Organization Among Neotropical Nectar-Feeding Birds

Abstract

Assemblages of neotropical hummingbirds are organized according to parameters of available resources and morphological-behavioral attributes of particular hummingbird species. We distinguish five types of flowers relative to hummingbird foraging, and we define six community roles for hummingbirds in exploitation of various flower types. These roles are: high-reward trapliners, which visit but do not defend nectar-rich flowers with long corollas; territorialists, which defend dense clumps of somewhat shorter flowers; lowreward trapliners, which forage among a variety of dispersed or nectar-poor flowers; territory-parasites of two types (large marauders and small filchers); and generalists, which follow shifting foraging patterns among various resources. Simple communities on islands usually contain one species of low-reward trapliner or generalist and one territorial species, and sometimes support one high-reward trapliner; often these species are sexuallydimorphic. More complex mainland communities support varying numbers of species in different roles, depending on the relative importance and constancy of different flower types. High-reward trapliners are particularly important in forest under-stories, while forest canopies and open habitats support large numbers of shorter-billed, mobile birds filling the other five roles. We conclude by pointing out the many parallels that exist with other consumer groups.