Dynamics of range expansion by three introduced species of Anolis lizards on Bermuda

Three species of Anolis lizards were introduced in this century to Bermuda, an archipelago formerly lacking anoles. A previous study conducted in the early 1960s indicated that A. grahami, the first species introduced, rapidly expanded over almost all of the archipelago. By contrast, the other two species had only attained limited ranges by 1963. I surveyed the extent of range expansion by all three species in 1991 and studied habitat use and behavioral interactions. All three species have been able to expand their ranges into areas occupied by other species, but the rate of range expansion has been relatively slow. The species are ecologically similar, but subtle differences in habitat use exist. Behavioral interactions indicate that A. grahami aggressively responds to conspecifics, displays less aggressively to A. extremus, and flees from the larger A. leachi.