Lesser Antillean snake faunas: distribution, ecology, and conservation concerns

Abstract

Thirty-three islands in the Lesser Antilles range in area from 0.06 to 1,510 km² and harbour 25 species of snakes representing five families and 10 genera. The islands have suffered at least six, and possibly as many as 11, historical extirpations and at least one historical extinction. The number of snake species per island is 1–5, and species richness is correlated with island size and habitat diversity. Islands that harbour three or more species exhibit greater habitat diversity, are larger, have a higher maximum elevation, and are situated closer to the South American mainland, the source area for most genera. North of the Guadeloupe Archipelago, islands support one or two species (an Alsophis or an Alsophis and a Typhlops). From the Guadeloupe Archipelago southwards, snake faunas have species belonging to genera that are widespread on the Neotropical mainland: Boa, Corallus, Chironius, Clelia, Liophis, Mastigodryas and Bothrops. Between 50 and 75% of the Lesser Antillean snake fauna preys on Anolis lizards. Snake faunas in the Lesser Antilles are not saturated, and many islands could support additional species; fossil evidence and written records indicate that they did. The islands have a 5,000-year history of habitat alteration, but introduced predators probably have had the greatest negative impact on snakes. The potential establishment of an alien snake (e.g. Elaphe guttata) into the Lesser Antilles is a valid concern. Preventing additional introductions of alien predators and protecting satellite island populations of threatened species are the two most important mechanisms for snake conservation in the region.