Foraging by Passerine birds and Anolis lizards on St. Eustatius (Neth. Antilles): implications for interclass competition, and predation

Abstract

Observations of foraging and diet for eight Passerine bird, two Anolis lizard, and one Ameiva lizard species in dry sclerophyll scrub on St. Eustatius (Neth. Antilles) show that none of the bird species competes as much with either anole as does the other anole, or the Ameiva. Anoles feed on insects, primarily on the ground and in low vegetation; on St. Eustatius no mainly insectivorous bird species feeds primarily in these places. Instead, the main presentday interaction between birds and anoles is predation. The abundant pearly-eyed thrasher (Margarops fuscatus) and the sparrow hawk (Falco sparverius) are the major predators on anoles. This predation has little effect on the niche relations of the anoles, according to a model for the coevolution of competing species.