|Scientific Name:||Iguana delicatissima|
|Species Authority:||Laurenti, 1768|
|Taxonomic Notes:||For discussion concerning the ambiguity of the Lesser Antillean Iguana (Iguana delicatissima) type specimen, see Breuil (2002) and Pasachnik et al. (2006).|
|Red List Category & Criteria:||Endangered B1ab(i,ii,iii,iv,v) ver 3.1|
|Assessor/s:||Breuil, M., Day, M. & Knapp, C.|
|Reviewer/s:||Grant, T.D. & Hoffmann, M.|
Based on historic range data, the total population has most likely experienced declines of ≥70%, the majority of which occurred soon after European contact rather than within the last three generations (11-14 years per generation). The current extent of occurrence of the species is estimated at not more than 3,000 km² and the existing population is severely fragmented. Moreover, only three subpopulations are considered stable and several have been extirpated within the last decade. The drivers for recent extirpations have not been mitigated and the likelihood of containing these threats without proactive management is unlikely (most notably the spread of Green Iguana). The species therefore qualifies for an Endangered listing.
Historically, this species is believed to have existed throughout the northern Lesser Antilles, from Anguilla to Martinique. Its range included (main islands only): Anguilla; Saint-Martin (French West Indies and Netherlands Antilles); St.-Barthélemy, including the island of Île Fourchue and its two small satellites (Îlet au Vent and Petite Islette), Îlet Frégate and Îlet Chevreau (or Bonhomme); St. Eustatius (Netherlands Antilles); St. Kitts and Nevis; Antigua and Barbuda; Guadeloupe, including the islands of Grande-Terre, Basse-Terre, Îles de la Petite Terre (comprising Terre de Bas and Terre de Haut), La Désirade, Les Îles des Saintes (comprising Terre-de-Bas, Terre-de-Haut, and Ilet à Cabrit), and Marie-Galante; Dominica; and Martinique, including Îlet Chancel and Îlet à Ramiers (introduced in 2006).The Lesser Antillean Iguana has since been extirpated from Saint-Martin (French and Dutch sides), Antigua, Barbuda, St. Kitts, Nevis, and Marie-Galante (Powell 2004). Ongoing surveys conducted on Guadeloupe since 2007 by Groupe d’Étude et de Conservation de l’Iguane des Petites Antilles en Guadeloupe (GECIPAG) suggest that populations have been extirpated recently from Grande-Terre and Les Îles des Saintes. It is also likely that iguanas have been extirpated from the islands of Îlet Frégate and Îlet Chevreau in Saint-Barthélemy (M. Breuil pers. comm. 2009).
Native:Anguilla; Dominica; Guadeloupe; Martinique; Saint Barthélemy
Regionally extinct:Antigua and Barbuda; Saint Kitts and Nevis; Saint Martin (French part)
|Range Map:||Click here to open the map viewer and explore range.|
Formal surveys using transect techniques have been conducted for Les Îles de la Petite Terre (Guadeloupe) and by mark-recapture for Îlet Chancel (Martinique). Rough population estimates for the remaining islands are based on limited surveys designed predominantly to locate iguanas for morphometric and genetic data collection. These population estimates are based subjectively on comparisons of observed density of iguanas and the extent of their range within each island. The population from Dominica is also estimated using site-specific mark-recapture data from 2007-2009 (C. Knapp pers. comm. 2009). Qualitatively, Dominica is believed to support the largest population (10,000-15,000 adults) due to the extent of available coastal habitat and known distribution, while Les Îles de la Petite Terre support the highest population density. However, many populations have been reduced to extremely low levels and limited areas such that their long-term viability is uncertain.
In Guadeloupe, since 2001, populations are now extirpated from Grande-Terre (Breuil et al. 2007), and Terre-de-Haut, Terre-de-Bas, and Îlet à Cabrit (Les Saintes) where Green Iguana (Iguana iguana) is now common. Individuals are still present in small numbers on Basse-Terre though their persistence is likely to be short-lived since Green Iguana and hybrids are now also present (Breuil et al. 2007, M. Breuil and GECIPAG pers. comm. 2009). Green Iguana is absent from La Désirade and thus large concentrations of Lesser Antillean Iguana persist at various sites. Lesser Antillean Iguana is now extirpated from Marie-Galante. The first estimation of the population of Les Îles de la Petite Terre (4,000–6,000 adults) was conducted in 1992-1993, three years after Hurricane Hugo (Breuil 1994a, Breuil et al. 1994). A second estimate was conducted by Lorvelec et al. (2007), but the results are questionable because of sampling methodology (Breuil and Ibéné 2008). Nonetheless, there seems little doubt that the two small islands are home to several thousand individuals (M. Breuil pers. comm. 2009).
The population of Chancel in Martinique has been monitored since 1993. In 1994, the population was estimated at approximately 250 adults (Breuil 1994b). More recent estimates using mark-recapture suggest a population size between 650 (Ourly 2006) to 950 adults (Legouez 2007). Estimates from 2009 suggest that the population now numbers more than 1,000 adults (M. Breuil pers. comm.). The increase is likely due to a decrease in hunting, an increase in tree cover from ~20% in 1947 to ~50% today, improvement and protection of the two historical nesting sites (Breuil 2000a,b; Legouez 2007), and control of domesticated, free-roaming dogs. Elsewhere in Martinique, nine adults were reintroduced to a small island, Ramier, in 2006 (Ourly 2006) and in 2008 a nest was found with hatched eggs. A few subpopulations of Lesser Antillean Iguana persist on the main island of Martinique and are protected, however introduced Green Iguana is also present (Breuil 2000a).
The current status of populations in Saint Barthélemy is unclear. On the main island, Lesser Antillean Iguana is found in a few areas, some of which support high densities; however, Green Iguana and hybrid individuals are also now known. Surveys in the early 2000s found a few lone individuals on Île Fourchue and its two small satellite islands (Îlet au Vent and Petite Islette) and it is not known if reproduction is occurring (Breuil 2001). Though reported by Lazell (1973), iguanas were not found recently on Îlet Frégate or Îlet Chevreau (Bonhomme).
Elsewhere in the Lesser Antilles, the species is now believed extirpated on Saint-Martin (where Green Iguana is now present) and from St Kitts, Nevis, Antigua, and Barbuda.
|Habitat and Ecology:||
The Lesser Antillean Iguana occupies islands of the northern Lesser Antilles from sea level to approximately 1,000 m (on Dominica). The species exists in xeric scrub, dry scrub woodland, littoral woodland, and mangrove, as well as lower and mid-altitude portions of transitional rainforest. The present condition of these habitats varies from island to island. Iguanas are able to survive in extremely xeric degraded habitats (less than 1,000 mm annual rainfall) to mesic forests (3,000-4,000 mm annual rainfall) in the absence of introduced predators or competitors.
Both hatchlings and juveniles live predominantly among bushes and low trees, usually in thick vegetation offering protection, basking sites, and a wide range of food. With age they climb higher and inhabit larger trees.
The species is a generalist herbivore, feeding primarily in the morning, with a diet that includes leaves, flowers, and fruits of a wide range of shrubs and trees. Seasonal variation in feeding ecology exists, with folivory during the dry season shifting to folivory and frugivory during the wet season. Feeding is selective with fresh leaf growth, flower buds, and ripe fruits preferred. Seed dispersal by iguanas may be significant for a number of coastal forest plant species, especially those with large or unpalatable fruits which are not dispersed by small birds or bats. Differences in feeding ecology between populations reflect local variation in plant species composition (either natural or as a result of introduced browsers). Like its congener the Green Iguana, the species has been observed to be opportunistically carnivorous (Lazell 1973).
Sexual maturity is reached at approximately two to three years, although breeding in young males is likely limited due to their inability to achieve dominance and defend a suitable territory. Longevity studies have yet to be conducted, but recent data suggest that individuals could reach 25 years in age. Generation length is estimated to be 11-14 years (C. Knapp pers. comm. 2009). Nest sites occur in sandy but also in clayish, well-drained soils exposed to prolonged sunlight. Clutch size, which may vary geographically, ranges from 8-18. Anecdotal evidence suggests an incubation period of approximately three months.
Habitat loss and fragmentation were historically most extensive on the least mountainous islands, which have been systematically cleared for agriculture, especially sugarcane. On these islands, the species has either become extinct (for example, St. Kitts and Nevis) or remains only in tiny remnant populations (for example, St. Eustatius). As tourism has superseded agriculture in importance, coastal development has further reduced the remaining habitat and significantly affected already limited communal nesting sites.
Road casualties occur regularly along coastal roads which bisect iguana habitat in Dominica, Basse-Terre and La Désirade (Guadeloupe), and St. Barthélemy. In Dominica, casualties peak late in the dry season when numerous gravid females are killed while migrating to coastal nest sites and early in the wet season when hatchlings disperse inland from nests. On La Désirade, there has been an increase in the number of off-road vehicles and a corresponding increase in deaths.
The species is impacted by a range of non-native introduced predators. Feral and pet cats are believed to be significant predators of juvenile iguanas on Anguilla, and predation by cats and dogs is a problem on Dominica. On St. Barthélemy, feral predators are few, but adult iguanas are known to be killed by guard dogs that run free within fenced properties where iguanas move to feed. Hatchlings and juveniles are within the prey range of mongooses (Herpestes javanicus [=auropunctatus]) and the species is either extinct or highly threatened on all islands where mongoose occurs (for example, Antigua and Barbuda). However, it is unclear how significant the impact of the mongoose is compared with other factors such as cats since Green Iguana remains common in mongoose-inhabited islands. Finally, raccoons (Procyon lotor) may pose a problem on La Désirade and other parts of Guadeloupe.
Free-ranging and feral browsing competitors are present among almost all iguana populations, with the notable exceptions of Iles de la Petite Terre and most of Dominica. Goat and sheep populations are particularly large and of most concern on Anguilla, La Désirade, St. Eustatius, and the islets of Saint-Barthélemy (Fourchue, Bonhomme, Frégate) where extensive over browsing continues to cause a shift in plant species composition and habitat structure (Breuil 2002).
Historically, hunting occurred throughout the range of the species since the time of the Amerindians. Hunting is now illegal throughout the species’ range. However, St. Eustatius has recently experienced a dramatic rise in iguana hunting, causing a crash in the population. Increased hunting has been linked to an influx of construction workers for the expansion of oil storage facilities on island and economic problems caused by changes in European Community regulations. Despite recent local legislation, iguana meat continues to be sold locally and transported to restaurants in nearby St. Martin. Hunting also remains locally prevalent in parts of Dominica, where certain populations have experienced rapid unsustainable exploitation (A. James pers. comm. 2009).
The species is legally protected from hunting throughout much of its range (it is listed in CITES Appendix II), but enforcement of these regulations is extremely difficult and therefore limited. In Dominica, the species is not formally listed as protected and there is a need to amend the Forestry and Wildlife Act to include provisions for the iguana.
The species is found in several nationally protected areas including the four national parks in Dominica, Les Îles de la Petite Terre (Guadeloupe), the Quill and the Boven (St. Eustatius), and Îlet Chancel and the Reserve Biologique Domaniale de la Montagne Pelée (Martinique). A number of satellite islets around Anguilla, Antigua, Guadeloupe, Martinique, St. Martin and St. Barthélemy offer significant potential to be established as protected areas.
In 2007, the French government commissioned an action plan to propose conservation measures in a concerted effort to protect this species (Maillard and Breuil 2007, Breuil et al. 2007, Legouez 2007). Since 2007, extensive fieldwork has been conducted in Guadeloupe and Martinique. Although the action plan was approved in June 2010, funding remains absent for the majority of specified actions.
Education and public outreach efforts are necessary throughout the range. In Dominica there is a critical need to develop an identification guide to assist officials in distinguishing Lesser Antillean Iguana from Green Iguana in order to ensure the latter species is not introduced to Dominica.Captive Lesser Antillean Iguana originating from Dominica are currently maintained at the Jersey Wildlife Preservation Trust and Chester Zoo (UK), and Fresno’s Chaffee Zoo (US). Reproduction has occurred but with variable success (M. Goetz pers. comm. 2009). As the Dominican population is presently healthy, these individuals and their future offspring should remain in captivity in order to gather husbandry expertise, as well as growth and reproductive data which can be applied to future in situ captive conservation efforts. Captive-raised iguanas could be used for reintroduction to suitable offshore islands and other protected areas, or for augmenting depleted populations. Reintroductions should originate with iguanas from the same geographic region whenever possible (as was the reintroduction at Ramier).
|Citation:||Breuil, M., Day, M. & Knapp, C. 2010. Iguana delicatissima. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 June 2013.|
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