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.


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