Roatán 2011 Field Update

Report submitted by Stesha Pasachnik

 

oedirhina_2011_update_Fig1The Roatán Spiny-tailed Iguana (Ctenosaura oedirhina) is endemic to the small and rapidly developing island of Roatán, located 48 km north off the Caribbean versant of Honduras, within the Bay Islands of Honduras. In March 2010, Daniel Ariano, Stesha Pasachnik, and the government of Honduras were successful in getting Roatán’s Spiny-tailed Iguana listed under Appendix II of CITES. Research leading up to this action brought to light how little was known about this Endangered species, despite the serious threats it faces. Thus, in July 2010, Stesha Pasachnik, working with the Bay Islands Foundation, began studying the basic biology of this species in hopes of creating a long-term management strategy and outreach and education program.

 

oedirhina_2011_update_Fig4 oedirhina_2011_update_Fig3Gaining an understanding of the threats this species faces was among the first and most important objectives of this project. Using data collected throughout 2010, Ctenosaura oedirhina was listed as Endangered under the IUCN Red List of Threatened Species. The primary threats to this species are harvesting and a limited and fragmented range. Iguana meat is eaten quite often by the local community and sold as an island delicacy to tourists. After surveying the entire island, we discovered that these iguanas can be found in all types of habitats, from mangroves to beach front, however decent populations can only be found in areas where grassroots protection efforts are in place, such as resorts and ecoparks. Thus, only isolated pockets of stable populations occur throughout the island. In addition the introduction of a wide ranging congener, C. similis, on a satellite island just off of Roatán poses a threat to the C. oedirhina population as there is the potential for extreme competition and hybridization if this non-native iguana colonizes Roatán itself. In order to mitigate this threat, we have been working with the owner and manager to eradicate this invasive species.

 

After surveying the island, we found three main sites across the island and one satellite island to use in the natural history research. Across these sites we have now marked approximately 500 individuals with bead and PIT tags. Morphometric data on these individuals indicates that both males and females are much larger than previously thought. An analysis of body condition indicates that males and females are not different in this respect, however, when considering body condition across sites we see that the areas that are more heavily developed with exotic plants have heavier animals. The health effects of this are still to be determined. Diet analysis shows that this species is much more omnivorous then previously thought and compared to other species of iguanas. These individuals have been observed eating crabs, turtles, and other iguanas. One of the strangest observations made throughout this study is of an adult individual with a regenerated leg appearing much like that of a regenerated tail! One of the greatest difficulties to date has been gaining an understanding of the reproductive behavior of this species. This is something that will need to be further investigated over the next few years, and luckily we have a new Ph.D. student joining the project, who is eager to take on this challenge.

 

oedirhina_2011_update_Fig2The development of a long-term education and outreach program focused on the protection of this Endangered species and its remaining habitats has been challenging. We have been successful in giving talks around the island and doing outreach with tour guides and tourists, however creating a formal teaching situation for teachers has not come to fruition as we expected. One of our biggest successes on this front is a coloring competition where children from all the public schools competed in coloring the endemic iguana and writing a unique fact about the species. A variety of local organizations have come onboard and donated some wonderful prizes. Creating a realistic management plan is something that is ongoing. We have been greatly successful in getting local organizations onboard as well as working with the national government. As time progresses and additional information is gained we will continue to develop our strategy and put it into action. Though there are currently no active means of protection, we have been greatly successful in raising awareness throughout the island. Additionally, there are grassroots efforts in place and through continued education we believe this force will grow, and we will be successful in protecting this Endangered iguana species far into the future.