|Scientific Name:||Ctenosaura bakeri|
|Species Authority:||Stejneger, 1901|
Enyaliosaurus bakeri (Stejneger, 1901)
|Red List Category & Criteria:||Critically Endangered B1ab(i,ii,iii,v)+2ab(i,ii,iii,v) ver 3.1|
|Assessor/s:||Pasachnik, S., Martinez, A. & Perez, M.S.|
|Reviewer/s:||Grant, T.D. & Hoffmann, M.|
|Contributor/s:||Randazzo, A., Castillo, J., Ariano-Sánchez, D., Montgomery, C.E., Burgess, J. & Köhler , G.|
The Utila Spiny-tailed Iguana is known only from the island of Utila, Honduras. Total known extent of occurrence is 41 km² but their area of occupancy is approximately 10 km². This iguana and its eggs are harvested and sold both locally and on the adjacent mainland. The primary threats to the population are habitat loss and fragmentation associated with development for tourism and decreasing quality of habitat from introduced invasive vegetation. The population is currently thought to be declining due to the above threats.
|Range Description:||The Utila Spiny-tailed Iguana is known only from the island of Utila, Bay Islands, Honduras. The extent of occurrence (EOO) is 41 km², although it is estimated that the iguana occupies less than 10 km² of the island (S.A. Pasachnik and L. Ehlke unpublished data). This iguana occurs from sea level up to 10 m asl.|
Native:Honduras (Honduran Caribbean Is.)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total population size is unknown, but could be less than 5,000 mature individuals. Although supporting documentation is lacking, it is believed the population is currently declining in correlation with increased habitat destruction over the last five to ten years and continued harvesting for human consumption. Genetic variation in the population does not follow a specific geographic pattern indicating that this iguana appears to be mating randomly across the island (Pasachnik et al. 2009).|
|Habitat and Ecology:||
The Utila Spiny-tailed Iguana is found primarily in mangrove forests and open beachfront areas, though they can be found in disturbed areas. Adults occur most often in the hollows of Black and White Mangrove trees, while juveniles occur in smaller mangrove trees, shrubs, and on the mangrove forest floor (Schulte and Köhler 2010). There is a dietary shift in these iguanas with age; juveniles seem to be primarily insectivorous, whereas adults feed arboreally and terrestrially on the flowers and leaves of mangroves, as well as crabs and other invertebrates.
The breeding season occurs in February and March. Mating occurs on the ground in the mangrove forests. The females then migrate from the mangroves to the sandy beaches, nesting most commonly in areas with full sun exposure. The nests can be a few meters long but not more than 60 cm deep; the nesting period is from mid March to June. On average females lay 11 to 15 eggs, though larger females have been known to lay 20 to 24 eggs. The incubation period is approximately 85 days. Hatching occurs from July through September. The hatchlings then move towards the mangrove forest and feed primarily on insects such as termites or flies. As hatchlings, they are an easy prey for birds such as the Great-tailed Grackle (Quiscalus mexicanus), Common Black Hawk (Buteogallus anthracinus) and Green Heron (Butorides virescens), snakes such as the Neotropical Racer (Dryadophis melanolomus), Mexican Parrot Snake (Leptophis mexicanus), Mexican Vine Snake (Oxybelis aenus), Green Vine Snake (Oxybelis fulgidus) and Boa Constrictor (Boa constrictor), and lizards such as Brown Basilisk (Basiliscus vittatus). Both the Common Black Hawk and Boa Constrictor have been observed to prey on adults.
The primary threat to this iguana is habitat loss and fragmentation due to infrastructure development for the tourist industry. Mangrove forest habitat is being used as garbage dumping sites and there is abundant deforestation for housing and marina construction. Beach habitat is being lost as natural vegetation is removed ("cleaning") in preparation for sale of properties and for hotel and road construction. Invasive alien plants are becoming more prevalent with development, which is making habitat inappropriate for egg laying. It has been shown that this iguana is capable of hybridizing with its wide-ranging congener, the Black Spiny-tailed Iguana (Ctenosaura similis). Although this is currently happening too infrequently to greatly threaten this species, hybridization could become a greater problem with increases in habitat destruction (Pasachnik et al. 2009). Dogs, cats, and rats are also present on the island and pose a threat to iguanas.
Although protected by Honduran law, the Utila Spiny-tailed Iguana and their eggs continue to be sought for human consumption, and are sold both locally and on the adjacent mainland.
The Utila Spiny-tailed Iguana is protected by Honduran law through a ban on hunting that has been in place since 1994. Actual enforcement of this law, however, is lacking, including within the Turtle Harbor Wildlife Refuge. In an effort to protect and raise awareness for these iguanas, the Utila Iguana Research and Breeding Station (IRBS) was established in 1997. Since 2008, the station has been run by a local non-government organization, The Bay Island Foundation (FIB). The IRBS conducts an environmental education programme, which focuses on environment awareness and protection of the iguana, their habitat, and other natural resources, and runs a breeding program with captive iguanas and wild gravid females, which produces approximately 150-200 juveniles per year. Captive-hatched juveniles are released on the beaches where the females were captured and also in other suitable mangrove forest areas corresponding to female capture sites. The IRBS is currently conducting a population study in six areas of Utila where Ctenosaura bakeri occurs. The study uses telemetry and mark-recapture techniques to assess the size and structure of the population. In addition, areas are checked for hunters and evidence of habitat destruction during these surveys.
In an effort to further reduce hunting, the Utila Spiny-tailed Iguana was recently listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Recommended conservation measures include active management and protection of the wild population and the creation of specific laws to protect this iguana at both the national and regional levels. Research needs include monitoring of population and habitat trends, as well as an in-depth study of the effects of harvesting on these iguanas.
|Citation:||Pasachnik, S., Martinez, A. & Perez, M.S. 2011. Ctenosaura bakeri. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 24 May 2013.|
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