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

Abstract

Thirty-three islands in the Lesser Antilles range in area from 0.06 to1,510 km 2 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 5,000year 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.

Molecular Phylogenetics of the Possibly Extinct Martinique Ground Snake

“…throughout different habitats (Schwartz and Henderson, 1991;Breuil, 2002). This trend was also confirmed by two studies on Erythrolamprus cursors' diet (Henderson 2004), finding both prey types and a small percentage of insects in their stomachs (Henderson and Bourgeois, 1993) in both E. cursor and E. juliae, which is not surprising considering local abundance of frogs and lizards (Ovaska, 1991;Roughgarden, 1995 , and the Turnip-Tailed Gecko (Thecadactylus rapicauda). Moreover, the Black Rat (R. rattus) and the House Mouse (Mus musculus domesticus) were probably introduced during the Napoleonic Wars (Breuil, 2009).…”

“…This is further supported by the fact that the small geographical distance between Dominica and Martinique (40 km) does not seem enough to prevent gene flow from one island to another for successful oversea dispersers such as snakes. Furthermore, the presence of Erythrolamprus endemics throughout the West Indies islands (E. perfuscus in Barbados, the extinct E. ornatus in Saint Lucia, E. cursor in Martinique, and E. juliae in Dominica, Guadeloupe, and MarieGalante; Henderson, 1992Henderson, , 2004Powell and Henderson, 2012) and the fact that these islands have never been joined geographically to others through land-bridge connections during past low sea levels (e.g., unlike Trinidad and possibly Tobago; Murphy, 1997) implies efficient marine dispersal (Hedges et al, 1992) and rafting (Boos, 1984a,b;Censky et al, 1998;Heinicke et al, 2007). In addition, the presence of E. juliae in different islands (although a taxonomical assessment is lacking), Guadaloupe, Dominica, and Marie-Galante, further supports the ability of these species to disperse over sea and colonize new habitats (Fig.…”

“…Because of their geography (33 islands of contrasting sizes) and the high level of endemisms, the Lesser Antilles poses a unique example to address biogeographical questions. These islands harbor 25 snake species (five families); 87.5% of them are endemic and some are among the rarest in the world (Henderson, 2004). Because island ecosystems are well known to be more vulnerable than continental ecosystems, the populations of such ecosystems are especially vulnerable to human disturbance (Simberloff, 2000).…”

“…Because island ecosystems are well known to be more vulnerable than continental ecosystems, the populations of such ecosystems are especially vulnerable to human disturbance (Simberloff, 2000). Furthermore, these islands have had at least six, and possibly as many as 11, historical extirpations (e.g., Alsophis, Erythrolamprus ;Henderson, 2004).…”

Living with or Eradicating Poisonous Snakes in Densely Populated Caribbean Islands—A Socio-Ecological Challenge for the French West Indies

“…Additionally, the challenges and the opportunities for biodiversity conservation are represented in particular by 120 snake species representing six families of which 115 are endemic to the Caribbean islands hotspot [2]. Whereas the species richness in the Lesser Antilles is only 25 snakes, the number of extirpations and extinctions is between six and 11 species [3]. The main cause of biodiversity loss is the habitat loss associated with the growth of human population size and density; populations of island snakes are isolated and they frequently have small areas of occupancy [4].…”