Use of premontane moist forest and shade coffee agroecosystems by army ants in western Panama

Two species of Neotropical army ant, Eciton burchelli and Labidus praedator (Hymenoptera: Formicidae: Ecitoninae), are swarm-raiding species that requ ire large areas of habitat in which to hunt. Behavioral and distributional studies of these two species have been confined largely to humid lowland fo rest. We conducted intensive systemic area searches at elevations between 1 200 and 1800 m in western Panama to assess the distribution of both species in intact premontane moist forest, shade coffee plantations close to fores t, and shade coffee plantations distant from forest. Neither species was ob served in sun coffee farm contributes to the persistence of these forest or ganisms in modified landscapes. Large canopy trees not only provide shade t hat buffers temperature extremes but also supply the ground layer with regu lar inputs of leaf litter and coarse woody debris as nesting sites (bivouac s). There were significantly fewer potential bivouacs available in sun coff ee plantations than in forest and shade coffee habitats. Also, it litter de pth was less in sun coffee than in forest and shade coffee. Our results pro vide the first evidence that shade coffee plantations can provide additiona l habitat for E. burchelli and L. praedator, top predators of the leaf litt er arthropod community. E. burchelli and L. praedator act as critical links between swarm-attendant bird species and leaf-litter arthopods, providing an easily exploited food resource that would otherwise be unavailable for m any birds. Continued conversion of shade coffee plantations to sun coffee p lantations could bare negative effects on army ants and associated biodiver sity.