[1]Lesser Antillean iguana (Iguana delicatissima) in a tree in Coulibistrie, Dominica. Image by Postdlf [2], CC BY-SA [3].
Often portrayed in action and adventure movies as either a giant, human-eating lizard [4]or a harmless pet [5], the iguana is a reptile native to South and Central America [6].
In the Lesser Antilles [7] in particular, two species have been observed over the last few decades: the common green iguana [8] (Iguana iguana) which is largely spread [9] throughout the region, and the Lesser Antillean iguana [10] (Iguana delicatissima), endemic to Anguilla [11], Dominica [12], Guadeloupe [13], Martinique [14], Saint Barthélemy [15] and Sint Eustatius [16].
Classified as a critically endangered [17] (CR) species in the Union for Conservation of Nature (IUCN) red list [18] since 2009, the Iguana delicatissima is threatened with extinction, despite initiatives being taken by regional governments and organisations — but is it already too late?
History of the species
The first iguanas appeared in the Antilles more than 7,000 years ago [19], when the region was still uninhabited. These reptiles were so common in the archipelago — especially in Saint Lucia [20] — that the indigenous Kalinago [21] named [22] the island Iouanalao, meaning “There where the Iguana is found”.
During the colonial era, these reptiles were chased and eaten [23] by both the Kalinago and the French, who considered them a good source of protein.
Only 13,000 to 20,000 adult iguana [19]still live in the Lesser Antilles, according to the IUCN. The majority of these — 10,000 to 15,000 [19] — is located in Dominica.
Buffering Dominica are the islands of Guadeloupe and Martinique, two French overseas departments that are also home to a significant population of Lesser Antillean iguanas.
Guadeloupe counted 4,000 to 6,000 iguanas [19] on its Petite-Terre islets [24] between 1992 and 1993, and identified nearly 400 adults [19] in the commune of La Désirade [25]. In Martinique, 800 to 1,000 individuals [26] were observed on the Chancel islet [27] in 2013.
In Anguilla, this number rose to 300 [19] in 1998, whereas in Sint Eustatius, the iguana population was somewhere between 275 and 650 [19] in 2004. Last but not least, 300 to 500 adults [23] may live in Saint Barthélemy.
In contrast, the Lesser Antillean iguana is believed to be extinct on the islands of Bonaire [28], Saba [29] and Saint Martin [30]. It has also completely disappeared on the archipelagos of Antigua and Barbuda [31] and Saint Kitts and Nevis [32].
Why the decline?
The decline of this species, whose life expectancy can at least reach 15 years [23], could be linked to two interconnected phenomena: competition [33] and hybridisation [34]. The first occurs when individuals (of the same or different species) are competing over a resource in order to survive and reproduce. The second happens when two similar species give birth to a hybrid offspring.
The incidence of the latter is increased by the resulting environmental impacts of intensive farming [35] and urban inrush [36]. Confronted with the deterioration of the vegetation and reduction of their natural habitats, the iguanas are compelled to live together in smaller spaces.
As a consequence, they tend to mate [37] regardless of their species. The common green iguana, therefore, threatens the existence of the Lesser Antillean iguana because of this crossbreeding, as their hybrid offspring contribute to a reduction in the “pure” Lesser Antillean iguana population.
Moreover, quite apart from having to cope with natural predators, among which are dogs and cats, [38] the Lesser Antillean iguanas are vulnerable to road accidents and hunting. [39]
Regional and international protection
Since the 1970s, governments around the world began to take measures to protect biodiversity. On March 3, 1973, 80 countries adopted the Convention on International Trade in Endangered Species of Wild Fauna and Flora [40] (CITES). This binding agreement, signed in Washington, DC, regulates the trade of 30,000 species of plants and 5,800 species of animals, including iguanas. [41]
A decade later, on March 23, 1983, 25 Caribbean states signed the Cartagena Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region [42], which grants protection [43] to the Iguana delicatissima. This Specially Protected Areas and Wildlife [44] (SPAW) protocol was signed on January 18, 1990, in Kingston, Jamaica. Both SPAW and CITES were ratified by Dominica, France, the United Kingdom and the Netherlands.
Some countries went further and added the conservation of the species into their own legislation. In 1989, for instance, a French ministerial order made it illegal to hunt, import or trade the Lesser Antillean iguana in Guadeloupe [45] and Martinique [46]. In Guadeloupe, the order initially protected the common green iguana as well, until it was withdrawn from the list of the protected species by an order [47] published on February 10, 2014.
On October 21 and 22, 2009, Dominica hosted a workshop on the conservation of the Lesser Antillean iguana. It served as a basis for the IUCN’s Conservation Action Plan [19], a document created to ensure the long-term survival of the species in the region.
Similarly, the French Ministry of Ecology launched two national action plans, covering the periods 2011-2015 [23] and 2018-2022 [26]. The current plan aims to protect the Lesser Antillean iguana by countering the proliferation of the green iguana.
An uncertain future
In Dominica and the French Caribbean, citizens are committed to conserving the Lesser Antillean iguana by halting the spread of the common green iguana.
The nonprofit organisation WildDominique [48], for instance, surveys and captures green iguanas [49], while educating Dominicans about the importance of conserving the Lesser Antillean iguana. Likewise, the volunteers of the Guadeloupe-based environmental organisation TITÈ [50] (Organisation for the Management of the Natural Areas of La Désirade) carry out catching operations, especially on the island of La Désirade and on the Petite-Terre islets. The success of these exercises is partly dependent on citizen engagement, as people are encouraged to call in whenever they sight a green iguana.
Still, much remains to be done. In Martinique, for example, the Lesser Antillean iguana is still classified as a critically endangered species [51] — the antepenultimate threat level before complete extinction — according to the IUCN's latest red list of threatened species in France, published on April 22, 2020.
Only time will tell if the Lesser Antillean iguana will survive or disappear. Yet, the announcement of the discovery of a new species of black endemic iguana [52] (Iguana melanoderma) on the islands of Montserrat and Saba on April 14, 2020, shows the unpredictability of nature.
Nevertheless, many feel that these hopeful signs must not relax conservation efforts.