Little is known of the ecological impacts of the exotic tree species tropical beach almond (Terminalia catppa) in the central Pacific of Costa Rica, but studies have found this species to be a potentially important resource for the recovery of endangered scarlet macaws (Ara macao). The goal of this study was to quantify the seed resource size provided by beach almond, estimate seed predation by variegated squirrels (Sciurus variegatoides) and scarlet macaws, and determine the extent of resource partitioning exhibited by the two predators. To answer these questions, reproductive phenology and seed predation were measured during March and April 2011 on beaches of the central Pacific coast of Costa Rica on a weekly basis for 111 beach almond trees. Seed productivity was quantified by visual surveys of flower, immature, and mature seed densities while seed predation was measured by collecting and sorting discarded shells by predation type.
Results/Conclusions
Seed production was large (about 160,712 seeds) while seed predation was low (about 32% of seeds). Macaw predation made up 67% of the seeds while squirrel predation accounted for 22% of the seeds. Evidence of spatial and temporal resource partitioning of the seed resource between squirrels and macaws was found. Scarlet macaws preferred to feed on the outer edge of trees while squirrels preferred to feed near the trunk. Both species ate most seeds on the ocean side of the tree but macaws fed more often on trees in an earlier reproductive state than squirrels. The resource size and occurrence of resource partitioning indicates that beach almond is an important food resource for scarlet macaws that should be considered in conservation efforts. However, more research is needed to assess other impacts of this exotic tree on beach communities in Costa Rica and around the world.