Five years of conserving the ‘world's rarest snake’, the Antiguan racerAlsophis antiguae

Abstract

The Critically Endangered Antiguan racer Alsophis antiguae is confined to Great Bird Island, a 9.9‐ha (24.5‐acre) islet off the north‐east coast of Antigua in the Lesser Antilles. This island represents well under 0.1 per cent of the species’s historical distribution range. During the past 5 years, the total number of racers aged 1 year or more has fluctuated between 51 and 114, and currently stands at approximately 80. Since 1995, the Antiguan Racer Conservation Project (ARCP) has endeavoured to save this harmless snake from extinction by using a combination of education, conservation breeding, habitat restoration, local capacity building and applied research. The Antiguan racer’s ecology and population dynamics have become well understood after 5 years of intensive study, and the species has evidently benefited from the project’s rat eradication programme. The snakes are still seriously threatened by other intrinsic and extrinsic factors, however, including inbreeding depression, frequent hurricanes, invasive predators and deliberate killing by tourists, as well as the problem that Great Bird Island is too small to support more than about 100 individuals. This paper describes the activities and impact of this project to date, and outlines a series of conservation activities to safeguard the long‐term future of the species, which include reintroduction of the Antiguan racer to restored islands within its former distribution range.

Marsupial Population and Conservation Genetics

“…22.1) have been translocated to six sites in western and central Australia (Finlayson et al, 2010) in attempts to re-establish populations. Although islands and island populations currently play a significant role in biodiversity conservation in Australia (and internationally, e.g., Lloyd and Powlesland, 1994;Daltry et al, 2001;Boessenkool et al, 2007;Cheke and Hume, 2008), it is becoming clear that the unique island environment (e.g., isolation, limited size, reduced ecological complexity etc.) Although islands and island populations currently play a significant role in biodiversity conservation in Australia (and internationally, e.g., Lloyd and Powlesland, 1994;Daltry et al, 2001;Boessenkool et al, 2007;Cheke and Hume, 2008), it is becoming clear that the unique island environment (e.g., isolation, limited size, reduced ecological complexity etc.)…”

Successful reintroduction of the Critically Endangered Antiguan racer Alsophis antiguae to offshore islands in Antigua, West Indies

“…No mortalities were recorded during translocation or the radiotelemetry studies and, when sighted, the released snakes were invariably in good condition. Although sample sizes were small, no obvious differences were detected between the activity patterns of the nine translocated individuals that were radio tracked in 1999 and 2002, and the five non‐translocated individuals that had been radio tracked on Great Bird Island in 1995 (Daltry et al ., ). Both genders typically alternated between several days of foraging activity followed by several days of remaining in a retreat, and moved on average 38 m per day.…”

“…An education and outreach campaign was launched to reassure the public that Antiguan racers are harmless, raise awareness of their role in the environment and foster national pride. The campaign employed national media and promoted the Antiguan racer through documentaries, stamps, T-shirts and other materials (Daltry et al, 2001). Although the species was traditionally called the 'grass snake', the name 'Antiguan racer' was deliberately introduced to reinforce the national identity of the species and avoid the negative connotations of the word 'snake'.…”

“…The Antiguan racer's genetic viability is another concern. The small source population on Great Bird Island was probably isolated for hundreds of years and exhibits many signs consistent with inbreeding, such as a high prevalence of congenital deformities and low fertility (Daltry et al, 2001). To combat further genetic erosion in any of the four populations, small numbers of racers should continue to be moved between the Islands for outbreeding purposes.…”

“…The racer's presence was confirmed when three specimens were collected in the mid‐1960s and another in 1987 (Henderson & Sajdak, ). A mark–recapture study in 1995 found only 51 ± se 7 individuals remained, of which half had injuries consistent with bites by Black rats Rattus rattus , which were abundant on Great Bird Island (Daltry et al ., ). This finding prompted the formation of the Antiguan Racer Conservation Project (now also known as the Offshore Islands Conservation Programme) by the government's Forestry Division (St John's, Antigua) and Environmental Awareness Group of Antigua & Barbuda (St John's, Antigua), and three international organizations: Durrell Wildlife Conservation Trust (Jersey, Channel Islands), Fauna & Flora International (Cambridge, UK) and Island Resources Foundation (St Thomas, US Virgin Islands).…”