HABITAT USE AND ECOLOGICAL INTERACTIONS OF AN INTRODUCED AND A NATIVESPECIES OF ANOLIS LIZARD ON GRAND CAYMAN, WITH A REVIEW OF THE OUTCOMES OF ANOLE INTRODUCTIONS

Since its introduction ten years ago, Anolis sagrei has spread over mu ch of Grand Cayman and is now more common in some habitats than the na tive anole, A. conspersus. Interspecific differences in body size, per ch height, and microclimatic preference may have facilitated the colon ization. Nonetheless, competition may be occurring between the species ; comparisons with studies of habitat use prior to the arrival of A. s agrei indicate that in open habitats, where A. sagrei is now abundant, A. conspersus perches higher, but in closed habitats, where A. sayrei is absent, no change in perch height is evident. Review of data conce rning 23 Anolis introductions indicates that the presence or absence o f an ecologically similar native species may be an important determina nt of colonization success or failure.