AVIAN NEST PREDATION IN TROPICAL WET FOREST - AN EXPERIMENTAL-STUDY

I used artificial nests to examine predation on birds' nests in lowland wet forest in Costa Rica. My purpose was to assess patterns of latitudinal variation in nest predation intensity and to predict the effects of further fragmentation of this forest on its associated avifauna. Nest loss did not vary among sites or between dry and wet seasons within the primary forest interior during 1988. Nests near forest/second growth edges were destroyed more frequently than nests in the forest's interior. Nest loss near forest/pasture edges, however, was similar to that in the forest interior. Nest loss was higher at five smaller (< 100 ha) than at three larger forest patches. Predation intensity at this site was comparable to that observed in three similar studies conducted in temperature forests. Comparative data from this site indicate that predation on nests of ground-dwelling birds at Barro Colorado Island, Panama, may be unusually high due to elevated densities of nest predators. High mortality rates of birds' nests previously reported for tropical forests could be an artifact of studying birds in disturbed or isolated forests.