Taxon Name: Iguana delicatissima Laurenti, 1768
• English: Lesser Antillean Iguana, West Indian Iguana
• French: Iguane des Petites Antilles
Red List Category & Criteria: Critically Endangered
Year Published: 2018
Date Assessed: March 3, 2018
Based on historic range data and an estimated index of abundance, the total population has experienced declines of ≥ 75%. Although extirpation from some islands occurred in the early to mid- 20th century, the remaining population has continued to decline within the last three generations (33–42 years). In recent years, on-going decline and extirpation of the Lesser Antillean Iguana has been primarily caused by inter- and intra-island dispersal of the invasive alien Common Green Iguana and subsequent hybridization. Common Green Iguanas are much more vigorous reproductively compared to native Lesser Antillean Iguanas, and hybridization and displacement is rapid post-introduction. Since the last assessment (2010), Common Green Iguanas have been observed among three additional pure populations (St. Eustatius, La Désirade, Ramiers), including the site of a recent native iguana reintroduction detailed in the previous regional action plan. These dispersals have not been mitigated and there is no likelihood of containing these threats without more proactive management. The current AOO of the species is estimated at less than 1,000 km2, the existing subpopulations are fragmented among isolated locations, and the large majority of the current range exists on one island (Dominica).
Population numbers for all islands is not available for multiple past generations, however their former area of occupancy can be estimated from published observations and an estimate of abundance based on habitat availability and quality. To project future population reductions, an annual rate of decline in AOO was calculated from the islands invaded by Common Green Iguana, from the known date of invasion to the present, and the remaining area occupied by pure subpopulations. Rates were applied to similarly-sized islands and assuming the worst-case scenario of invasion of remaining pure populations within the next few years. It is strongly felt the risk of invasion and extirpation of the remaining pure populations is imminent in the wake of increased post-hurricane shipping among islands in both species’ range, and the lack of biosecurity to mitigate this threat. The recent increase in illegal poaching is also a significant threat to the species’ persistence.
Under these projection parameters, within one generation, five of the remaining pure populations plus four of the currently invaded/hybridized locations will be extirpated. Only 13% of the species’ current AOO is predicted to remain three generations from now.
This is a genuine change from the most recent assessment due to increasing occurrence and rate of hybridization and island extirpations.