Vertebrate predation of Brazil-nuts (Bertholletia excelsa, Lecythidaceae), an agouti-dispersed Amazonian seed crop: A test of the escape hypothesis

The effects of escape distance to parental trees and tree clusters on the removal of Brazil-nut seeds (Bertholletia excelsa, Lecythidaceae) by vertebrate seed predators were examined in an entirely undisturbed stand of Brazil-nut trees of eastern Amazonia. Population density estimates, based on line-transect censuses, are also presented for Bertholletia trees and agoutis (Dasyprocta leporina), the most important scatterhoarder and seed predator of Brazil-nuts at this site. Seed removal experiments were conducted within and outside a natural Bertholletia tree cluster (castanhal) during both the wet and dry seasons. While there were no withincluster effects of escape distance from parent trees on seed removal rates, overall seed removal within the cluster was significantly greater than that well outside the cluster. Moreover, removal rates in the wet season were consistently higher than those in the dry season both within and outside the tree cluster. Results suggest that the probability of early seed survival for Bertholletia, in relation to distance to seed sources, operates on different spatial scales, and that seed predators allocate greater foraging effort to scattered seeds during the fruitfall (wet) season, when buried seed stocks are being cached by agoutis.