Observations on the Foraging Ecology and Social Behavior of the Bridled White-Eye

I studied the foraging ecology and social behavior of the Bridled White-eye (Zosterops conspicillatus) on Saipan and Tinian, Mariana Islands. On Saipan, birds foraged in flocks of 10-40, and dominance relationships existed within flocks. The white-eye appeared socially subordinate to the other insectivorous passerines. Bridled White-eyes foraged principally on the outer crown of trees and shrubs, where they perched on relatively slender branches to glean invertebrates from leaf surfaces. They foraged similarly in two habitats, but they used a wider range of perch sizes in limestone forest than in tangantangan (Leucaena leucocephala) thickets. Hence, absolute vegetation height was of little importance to this species. Bridled White-eyes were versatile in their foraging, which included every microenvironment from the ground to treetops. They used gleaning, probing, hovering, and sallying to feed on invertebrates, nectar, fruits, and seeds.