Density and Feeding Preference of the Polillo Tarictic Hornbill Penelopides manillae subnigra in Fragmented Forests of Polillo Island

Abstract

The density and feeding preference of the Polillo hornbill Penelopides manillae subnigra were compared between a heavily disturbed secondary forest and a residual lowland forest. Using transect analysis, the density of tarictics in each forest site was computed. The disturbed forest site exhibited higher tarictic density (4.75 individuals per km²) than the residual forest site (1.25 individuals per km²). The difference in tarictic density between the two sites was affected by several factors, such as the abundance of fruiting trees, the presence of nesting trees and also the degree of anthropogenic disturbance. The disturbed forest site was more fragmented (20% forested area) than the residual forest site (26% forested area). Both forest sites were suitable for sustaining tarictic populations. The disturbed forest site contained more fruiting trees foraged and dispersed by tarictics, thus a higher density was observed. In the residual forest, large trees were observed that are essential for nesting during the breeding season. Male tarictics are territorial especially during this time thus they drive away other tarictics to protect their nests and as a result, a lower density was observed. Forests of Polillo have undergone fragmentation. Being endemic, tarictics tend to tolerate anthropogenic disturbances to the forest habitat.