Some Niche Differences in Three Lesser Antillean Lizards of the Genus Anolis

Abstract

This paper documents interspecific and intraspecific differences in certain niche parameters among 3 species of lizards of the genus Anolis occurring in the southern Lesser Antilles. The 2 species whose ranges broadly overlap in Grenada show significant differences in body temperatures and food size distributions. Although there is considerable difference in the maximum size attained by the 2 species, animals with identical head and body lengths have radically contrasting distributions of prey size: smaller individuals of the larger species take larger food than larger individuals of the smaller species. The rate of increase of average prey length with increasing head length for the smaller species is lower than that for the larger one. In all species, the larger adult makes take significantly larger prey than adult females or subadult males. For the 2 species on Grenada, adult females take significantly smaller food than subadult males of the same species and head length; there is a slight reversal of this trend for the solitary species on Martinique. For all 3 species, adult males eat a greater amount of plant matter and draw more of their prey from fewer taxonomic categories than do lizards of the smaller—sized classes, In general, as the size of lizard increases, range of prey size increases and the number of prey items ingested decreases; variances for these distributions are quite large. Modes of niche segregation on Grenada are contrasted with those among anoles of other small islands, and hypotheses are offered as to how climatic features and the spatial arrangement of individuals of varying size within a species might determine the critical niche dimensions.