Burg, M.P. van den

Illegal trade of morphologically distinct populations prior to taxonomic assessment and elevation, with recommendations for future prevention

The negative impacts of international wildlife trafficking are well known, and such negative impacts can be even more pronounced for insular species. This dynamic market needs close monitoring, and when novel species appear in the commercial trade, relevant authorities should be able to react to reduce negative impacts on wild populations. Here we describe a novel case where an insular endemic population of the Iguana iguanacomplex has entered the international commercial trade, likely stimulated by efforts to elevate the population taxonomically. Despite the absence of authorized export permits from the relevant CITES authority, we identify animals that are sold in a range of countries and the likely pathway and methods of importation. We provide recommendations to prevent future illegal collection and trafficking that could be implemented for other taxa. We call for increased awareness of the higher economic value of taxa considered for future taxonomic elevation, and increased monitoring of the commercial trade in order to act promptly when illegal activity is detected. 

Keywords

CITES legislation, Commercial trade, Iguana iguana, Illegal trade, Laundering, Pet trade

 

Date
2020
Data type
Scientific article
Theme
Governance
Legislation
Geographic location
Saba
St. Eustatius
St. Maarten

Iguana delicatissima. The IUCN Red List of Threatened Species 2018: e.T10800A122936983

Taxon Name: Iguana delicatissima Laurenti, 1768

Common Name(s):

• English: Lesser Antillean Iguana, West Indian Iguana

• French: Iguane des Petites Antilles

Assessment Information

Red List Category & Criteria: Critically Endangered

Year Published: 2018
Date Assessed: March 3, 2018

Justification:

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.

Date
2018
Data type
Other resources
Geographic location
St. Eustatius

Anthropogenic Mortality in the Critically Endangered Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius

The Lesser Antillean Iguana, Iguana delicatissima (Laurenti 1768) is a Lesser Antillean endemic (Anguilla to Martinique, with the exception of Saba and Montserrat). The IUCN Red List status of this species was recently elevated from Endangered (Breuil et al. 2010) to Critically Endangered (van den Burg et al. 2018a). Population declines are driven by habitat loss, anthropogenic mortality, and invasive predators, but on many islands the declines are the result of hybridization with and displacement by the non-native invasive Iguana iguana (Linnaeus 1758) (Knapp et al. 2014; Vuillaume et al. 2015; Breuil et al. 2010; van den Burg et al. 2018a). In fact, genetically pure populations currently inhabit only 22% of the species’ historic distribution, and populations have been extirpated on Antigua, Barbuda, St. Kitts, Nevis, St. Martin/Maarten, Grand-Terre, Marie Galante, and Les Îles des Saintes. Recent discoveries of non-native iguanas on La Désirade and Dominica are extremely worrisome (e.g., Association Ti-Té 2017) and highlight the need for region-wide biosecurity improvements. Remnant populations on islands invaded by Iguana iguana (Anguilla, St. Barthelémy, St. Eustatius, Basse-Terre, and Martinique) also are likely to become extirpated unless on-going hybridization is prevented and remaining non-native iguanas removed. With few remaining populations and continuing anthropogenic pressure, information about these last populations’ health and threats are crucial to the species’ survival.

The Dutch Caribbean island of Sint Eustatius (21 km2) supports a small remnant I. delicatissima population (Debrot et al. 2013; van den Burg et al. 2018b; Fig. 1). Although this population almost certainly experienced declines since European settlement as a result of extensive island-wide agricultural practices (e.g., Chambers and Chambers 1842), numbers declined even further due to intensified hunting practices at the end of the 20th Century. The recently discovered threat of hybridization plus low recruitment, low availability of nesting sites, and anthropogenic mortality pose an ongoing severe threat (Debrot et al. 2013; van den Burg et al. 2018b). We hereby expand on a public survey undertaken in 2012 (Debrot and Boman 2014) to assess current threats and causes of mortality within the I. delicatissima population on St. Eustatius and make recommendations for the recovery of this remnant population.

 

Date
2018
Data type
Scientific article
Theme
Research and monitoring
Geographic location
St. Eustatius

The Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius: genetically depauperate and threatened by ongoing hybridization.

The Lesser Antillean Iguana (Iguana delicatissima) is an endangered species threatened by habitat loss and hybridization with non-native Green Iguanas (Iguana iguana). Iguanadelicatissima has been extirpated on several islands, and the Green Iguana has invaded most islands with extant populations. Information is essential to protect this species from extinction. We collected data on 293 iguanas including 17 juveniles from St. Eustasius, one of the few remaining I. delicatissima strongholds. Genetic data was leveraged to test for hybridization presence with the Green Iguana using both mitochondrial and nuclear genes, including 16 microsatellite loci. The microsatellites were also analysed to estimate genetic diversity, population structure and effective population size. Using molecular and morphological data we identified 286 I. delicatissima individuals captured during our first fieldwork effort, and seven non-native iguanas captured during a second effort, showing hybridization occurs within this population. Comparing homologous microsatellites used in studies on Dominica and Chancel, the I. delicatissima population on St. Eustatius has extremely low genetic diversity (HO=0.051; HE=0.057), suggesting this population is genetically depauperate. Furthermore, there is significant evidence for inbreeding (FIS=0.12) and weak spatial genetic structure (FST=0.021, p=0.002) within this population. Besides immediate threats including hybridization, this population's low genetic diversity, presence of physiological abnormalities and low recruitment could indicate presence of inbreeding depression that threatens its long-term survival. We conclude there is a continued region-wide threat to I. delicatissima and highlight the need for immediate conservation action to stop the continuing spread of Green Iguanas and to eliminate hybridization from St. Eustatius.

Date
2018
Data type
Scientific article
Theme
Research and monitoring
Geographic location
St. Eustatius