Útila Spiny-tailed Iguana
Ctenosaura bakeri
IUCN Status: Critically Endangered
Range: Útila Island, Honduras
Population: Unknown, estimated less than 5,000
Size: Up to 15.75 inches in length from snout to vent, 33.5 inches total
Threats: Habitat destruction for private and commercial development; hunting for food (particularly gravid females); predation by dogs, cats, raccoons, and rats
Conservation Measures

The Útila Spiny-tailed Iguana (Ctenosaura bakeri), or “Swamper” as it is known locally, is endemic to the island of Útila, which is located in the Bay Island archipelago off the Caribbean coast of Honduras. The island has an area of 15.8 square miles, although Ctenosaura bakeri is thought to occupy less than 3.9 square miles. These iguanas are primarily a mangrove dwelling species, however they are also found in coastal vegetated areas and use beaches for nesting. The current population size is not known but is thought to be fewer than 5,000 individuals. Further, the population is likely declining due to habitat loss and fragmentation, hunting of adults and eggs, and predation by invasive species. The Útila Spiny-tailed Iguana is listed as Critically Endangered by the IUCN Red List of Threatened Species. Despite being protected under Honduran National Law, enforcement is rare and poaching is a regular occurrence.

The IIF began funding research on Ctenosaura bakeri over 10 years ago. This early work focused primarily on collecting basic natural history data, conservation genetics, and documenting population status and habitat use. Habitat destruction has been shown to contribute to declining body condition of these iguanas. In addition, a decline in the number of females was documented, and is likely due to female-biased hunting pressures. Genetic analyses confirmed the presence of hybridization between C. bakeri and Ctenosaura similis, a widespread species that also naturally occurs on Útila. These rare hybridization events occurred in human-inhabited areas, suggesting that development may increase the risk of C. bakeri extinction by hybridization.
In recent years, the IIF has teamed up with the Kanahau Útila Research and Conservation Facility (KURCF – www.kanahau.com) and University of South Wales, to further assess the species and provide advice on proper management and conservation actions. Research areas include: a robust estimate of the current population, habitat use and home range analyses, nesting and reproductive ecology evaluations, and behavioral assessments. Radio transmitters are used to determine movement of adult iguanas across the island. This research has gathered information on home range and migration routes between breeding and nesting habitats, as well as some interesting predation observations. Over 100 habitat surveys have been completed to understand their preferred habitat and which areas are most at risk from development and potential hybridization events.
Concurrently, KURCF is conducting an education program in Útila’s local schools. This includes lectures on the iguana and their habitats, and also engages the local community by including students in population surveys in the mangroves. Future plans for the project by KURCF include raising funds for land acquisition to protect the habitat of the iguanas and other endemic animals on Útila.
Reports from the Field
IIF Grants Received