Abstract
While not generally considered charismatic mega-vertebrates, iguanas of the genus Cyclura are the largest endemic vertebrates in the Caribbean, among the most endangered lizards in the world, and are, in fact, quite charismatic!1 The International Union for the Conservation of Nature (IUCN) Iguana Specialist Group (ISG) has been developing Species Recovery Plans (SRP) for several of the most critically endangered species, and veterinary work has played a prominent role in these conservation efforts.2,4,5 Hispaniola is the only island in the Caribbean with two sympatric species of Cyclura. Ricord’s iguanas (Cyclura ricordi) are critically endangered (CR) according to the IUCN Red List and found only in four small, isolated populations. Rhinoceros iguanas (Cyclura cornuta) are considered vulnerable (VU) and are found in numerous habitats on the island. In 2002 the ISG met in the Dominican Republic to develop the Ricord’s Iguana SRP.3 This plan detailed a recovery process including surveys of iguana populations, floristic and ecological surveys, biomedical and genetic work, behavioral assessments, captive breeding, public awareness, and fund raising. Progress has been slow but steady. The local Nongovernmental Organization (NGO), Grupo Jaragua has concentrated its efforts on the populations south of Lago Enriquillo and has done considerable nest mapping, local education, and land procurement.9-11 An exciting recent development is the discovery of a small C. ricordi population in Haiti, and Grupo Jaragua is conducting a socioeconomic study of the people in the area, in relation to the iguanas and their habitat, as a first step in protecting that population.11
The Indianapolis Zoo has been working for the past nine years with the population of C. ricordi on Isla Cabritos, which is a Dominican National Park. Vitamin D, serum chemistry, microbiology, and morphometrics have previously been published, as have preliminary survey data.6-8 In 2005, collaborative efforts between Grupo Jaragua, Parque Zoological Nacional (Zoodom, the national zoo of the Dominican Republic), and the Indianapolis Zoo produced an iguana conservation curriculum designed for the third grade classroom. This curriculum was very popular during teacher workshops in 2006 and is now being implemented in Dominican schools.
Indianapolis Zoo also partners with Zoodom to assess the health of the animals in Zoodom’s thriving captive breeding program for C. ricordi. A comparison of biomedical parameters of the captive and free-ranging population of both C. ricordi and C. cornuta revealed some interesting differences. Preliminary results show that captive C. cornuta white blood cell counts are subjectively higher than for free-ranging animals, with no clinical signs of disease. This was not the case for C. Ricordi, where no difference could be detected. The captive C. cornuta are held in very large, multi-gender groups in relatively small enclosures, while the C. ricordi are in pairs in large enclosures. The observed increase WBC in captive C. cornuta may be attributable to chronic stress, and Zoodom staff are investigating other housing options. In 2008 a floristic study was initiated in hopes of developing a comprehensive nutritional profile of the food plants endemic to the iguana’s natural habitat. These data will not only allow for the distinction of individual plant species but also the determination of frequency and density of all plant populations including food plants found on the island. At the same time plasma samples were submitted to a commercial laboratory to determine mineral status from both captive and free-ranging iguanas. Preliminary data analysis has yielded interesting results with extensive discrepancies observed in both C. ricordi and C. cornuta. For example, selenium, which can be toxic in large doses to multiple species, was determined at an approximately seven-times-higher prevalence in free-ranging versus captive iguanas.12 The elevated levels of this metabolite yielded no apparent deleterious pathologies in the free-ranging subjects. Upon analysis, two plant species, Prosopis juliflora and Conocarpus erectus both exhibited selenium concentrations above 5.0 ppm. This information combined with fecal dissection data and extensive coverage class scores within the island terrain, identifies them as potentially significant food plants within the wild-type diet.
In addition to the biomedical, nutritional, and floristic work, Indianapolis Zoo and Zoodom staff continue annual iguana population surveys and hope to begin telemetry tracking in the coming years. This long-term, cooperative conservation program has been rewarding. Steady progress has been made in increasing our understanding of the biology and ecology of these animals, in local public conservation education, and finally in moving toward better protection for the fragile populations of this critically endangered species.
Acknowledgments
The authors thank Dr. Gerard Garcia-Dubus, Jennifer Niederlander, Renae Burks, Jon Pilarski, John Wyatt, Richard Searcy, and Richard Reams, the Lago Enriquillo Guides, Zoodom, and Grupo Jaragua for their hard work and support of this project. We also thank the Maine Community Foundation, U.S. Fish and Wildlife Wildlife Without Borders Program, AZA Conservation Endowment Fund, International Iguana Foundation, International Reptile Conservation Foundation, AAZV Mazuri Grant, AZVT Member Grant Fund, and Indianapolis Zoo for financial support.
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