Foraging ecology in the lizard Anolis oculatus (Iguanidae) from Dominica, West Indies



In general, populations of Anolis lizards on West Indian islands face few predators, are at high density and are thought to be limited by food. This paper describes how the foraging ecology of Anolis oculatus, a solitary species confined to the island of Dominica, Lesser Antilles, varies with habitat and season in relation to the quantity and quality of available food.

Availability of invertebrate food (determined using pitfall traps and sticky traps) was greater in a dry scrub woodland site, Cabrits National Park (CNP), compared with a montane rainforest site, Palmiste Ridge. In the former, there were general increases in abundance, volumes of softbodied prey and sizes of invertebrates from dry season to wet season. Concomitant dietary changes, as determined principally by stomach flushing, included an increase (by volume) in the proportion of soft-bodied prey. Dietary analyses confirmed the importance of ants (Formicidae) in the diet of A. oculatus, although for large individuals (mainly adult males) at the rainforest site, soft-bodied prey such as Oligochaeta and Orthoptera were, in volumetric terms, more important. Prey capture observations showed that large A. oculatus fed mainly above ground. Anolis oculatus at the montane rainforest site used higher perch heights than those in dry scrub woodland, although in both habitats, small individuals (mainly juveniles) fed mainly at ground level on ants. In the dry season in CNP, the diet (in volumetric terms) of smaller Anolis was dominated by hardbodied prey such as ants, springtails (Collembola), barklice (Psocoptera) and beetles (Coleoptera). large Anolis used springtails and barklice to a lesser extent, resulting in relatively low food niche overlap values between size classes and a reduced potential for intraspecific competition compared with the wet season.