Anoles of St. Vincent (Squamata: Polychrotidae): Population Densities and Structural Habitat Use

Abstract

We examined population densities and structural microhabitat use by Anolis griseus and A.trinitatis at eight sites on the leeward (western) coast of St. Vincent, West Indies. Estimates of population density based on the Schnabel method varied according to habitat complexity and ranged to 5,208/ha for A.griseus (a higher estimate at one site was not considered due to conditions that compromised the accuracy of estimates) and to 27,923/ha for A.trinitatis. Our highest estimate for both species at one site (32,867/ha) was the highest yet recorded for any site on a two-species Lesser Antillean island. For both species, larger individuals tended to perch higher and on perches of larger diameter than smaller lizards, with adult male A.griseus using the highest and largest diameter perches. However, considerable overlap in perch use among other size classes of A. griseus and all size classes of A. trinitatis suggests that structural habitat partitioning is not rigid in these two species. Although A. griseus was most abundant at densely shaded sites, A. trinitatis was essentially ubiquitous, supporting the predictions that these anoles were ecologically versatile and abundance and microhabitat use would reflect available vegetative structure.