The Condor 102:7X4-794 0 The Cooper Ornithological Society 2000 ANTBIRD GUILDS IN THE LOWLAND CARIBBEAN RAINFOREST OF SOUTHEAST NICARAGUA1 MARTIN L. CODY Department of OrganismicBiology, Ecology and Evolution, Universityof California, Los Angeles, CA 90095-1606, e-mail:
[email protected] Abstract. Some 20 speciesof antbirdsoccur in lowland Caribbeanrainforest in southeast Nicaragua where they form five distinct guilds on the basis of habitat preferences,foraging ecology, and foraging behavior. Three guilds are habitat-based,in Edge, Forest, and Gaps within forest; two are behaviorally distinct, with species of army ant followers and those foraging within mixed-species flocks. The guilds each contain 3-6 antbird species. Within guilds, species are segregatedby body size differences between member species, and in several guilds are evenly spaced on a logarithmic scale of body mass. Among guilds, the factors by which adjacent body sizes differ vary between 1.25 and 1.75. Body size differ- ences may be related to differences in preferred prey sizes, but are influenced also by the density of the vegetation in which each speciescustomarily forages. Resumen. Unas 20 especies de aves hormiguerasviven en el bosque tropical perenni- folio, surestede Nicaragua, donde se forman cinquo gremios distinctos estribando en pre- ferencias de habitat, ecologia y comportamiento de las costumbresde alimentacion. Las diferenciasentre las varias especiesson cuantificadaspor caractaristicasde1 ambiente vegetal y por la ecologia y comportamientode la alimentaci6n, y usadospara definir cinco grupos o gremios (“guilds”). Tres gremios se designanpor las relacionesde habitat: edge (margen), forest (selva), y gaps (aberturasadentro la selva); dos mas por comportamiento,partidarios de army ants (hormigasarmadas) y mixed-speciesflocks (forrejando en bandadasde especies mexcladas).