|Scientific Name:||Ctenosaura melanosterna (Cayos Cochinos subpopulation)|
|Taxonomic Notes:||Because this species was described relatively recently, it is often referenced in the literature as Ctenosaura palearis or Enyaliosaura palearis, the sister species that it was split from.|
|Red List Category & Criteria:||Critically Endangered B1ab(iii,v)+2ab(iii,v) ver 3.1|
|Assessor/s:||Pasachnik, S., Montgomery, C.E. & Henningheim, E.|
|Reviewer/s:||Grant, T. & Hoffmann, M.|
|Contributor/s:||Ariano-Sánchez, D., Burgess, J. & Ruyle, L.|
Within Cayos Cochinos the Black-chested Spiny-tailed Iguana is restricted to the two larger islands and a few very small satellite cays. The individuals on the small cays were most likely introduced by people and do not represent stable populations. Extent of occurrence and area of occupancy for this iguana is 2.2 km². Iguanas occur throughout the land space but there is a gradual decline in the quality of the habitat on both islands, and in the number of mature iguanas on Cayo Mayor. Declines will be transferred to Cayo Menor as hunting pressure has increased. The presence of invasive alien mammals on both islands threatens the iguana. In addition, increasing Common Green Iguana (Iguana iguana) populations on Cayo Menor poses a threat to the Black-chested Spiny-tailed Iguana population due to increased competition for forage. These factors combined with the close proximity of the two islands make this population highly susceptible to the impacts of any hurricane. Local extinctions of iguanas on small, low elevation islands has been observed after a hurricane for other iguana species in the Caribbean (Hayes et al. 2004).
This is a non-genuine change from the previous assessment due to misinterpretation of the criteria.
|Range Description:||The Black-chested Spiny-tailed Iguana is known only from the Valle de Aguán in northern Honduras and the Cayos Cochinos Archipelago off the Caribbean coast of Honduras, where it occurs primarily on the two largest islands: Cayo Mayor (Grande) and Cayo Menor (Pequeño). These two cays are approximately one kilometre distant from each other. The extent of occurrence is estimated to be 2.2 km² for the Cayos Cochinos subpopulation. This subpopulation occurs from sea level up to 140 m.|
Native:Honduras (Honduran Caribbean Is.)
|Range Map:||Click here to open the map viewer and explore range.|
The total population size is not known, but is estimated to be less than 3,000 mature individuals within the Cayos Cochinos. Although the geographic range of the Cayos Cochinos subpopulation is substantially smaller than for the Valle de Aguán subpopulation, the density of individuals throughout the Valle is extremely low, and it is believed iguana numbers are greatest on Cayos Cochinos (S.A. Pasachnik pers. obs. 2011). The population trend is currently stable on Cayo Menor (Pequeño), but recent increases in the population density of Common Green Iguana (Iguana iguana) may result in increased competition for resources. The population on Cayo Mayor (Grande) seems to be at low density, most likely due to hunting and predation by feral dogs. Hunting pressure has been seen to increase on Cayo Menor as local villagers from Cayo Mayor visit the island for additional resources. The Cayos Cochinos subpopulation is genetically distinct from the Valle de Aguán iguanas and has been described as a separate evolutionarily significant unit (Pasachnik et al. 2011).
|Habitat and Ecology:||
The Black-chested Spiny-tailed Iguana inhabits tropical and subtropical dry forest and scrubland from 0 to 140 meters above sea level (Holdridge 1967, Dinerstein et al. 1995). It is semi-arboreal and diurnal, taking refuge in hollow logs and rock crevices at night. On Cayos Cochinos, iguanas utilize forest edge habitat consisting of sandy beach strand vegetation and rocky cliffs, as well as areas of open forest, including tree fall gaps. This iguana is omnivorous, consuming fruit, flowers, leafy vegetation, arthropods, a variety of lizards, birds (especially fledglings), and carrion.
On Cayo Menor, marked sexual dimorphism in size has been observed with males being larger. Males are territorial, with multiple females and juveniles residing within the territory. Nesting takes place in sandy substrates from April through July, with 7-18 eggs laid per nest. Hatchlings emerge from June through September (C. Montgomery pers. comm. 2009).
In captivity, the Black-chested Spiny-tailed Iguana lives from 10 to 15 years and reaches sexual maturity at 2 to 3 years. They lay eggs twice a year in February/March and August/September. Clutch sizes range from 11 to 41 eggs. The incubation period ranges from 85 to 90 days. Hatchlings have a snout-vent length of 41-52 mm, a total length of 114-149 mm, and average weight of 4 grams (E. Henningheim pers. comm. 2009).
The primary threat to the Black-chested Spiny-tailed Iguana is habitat destruction and fragmentation. Limited habitat destruction occurs on both islands of the Cayos Cochinos as palm trees are harvested for thatch roofs (Wilson and Cruz-Nieto 1993). Additionally, feral dogs, cats, and rats exist on both Cayo Mayor and Cayo Menor and are predators of iguanas and their eggs. Increases in the Common Green Iguana (Iguana iguana) population may also pose a threat to the Cayos Cochinos population.
Adult iguanas and eggs are sought for both immediate consumption and sale. On Cayo Mayor, individuals are increasingly collected for consumption, but this threat is much more extreme within the Valle de Aguán. Illegal exportation for the international pet trade has also been documented for this iguana. Though individuals may be taken from Cayos Cochinos, all documented cases of excessive exploitation and exportation for the pet trade are from the Valle de Aguán. The exact number of animals being exported is difficult to determine because declaration of the species name is not necessary for importation and the exportation is illegal, thus undocumented. Exportation is largely to the United States and Europe. The cost of an individual iguana in the Valle de Aguán varies from $1 to 90 USD, depending on size and sex.
Cayos Cochinos is located within a Marine Natural Monument, and within the cays the Black-chested Spiny-tailed Iguana is offered protection from exploitation (although the level of protection and enforcement varies between islands). In an effort to reduce illegal trade and over-harvesting, the Black-chested Spiny-tailed Iguana was recently listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Research is needed on this iguana's life history and ecology. Conservation actions recommended include educational awareness and trade and harvesting regulation and enforcement at both the national and local level.
|Citation:||Pasachnik, S., Montgomery, C.E. & Henningheim, E. 2012. Ctenosaura melanosterna (Cayos Cochinos subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 17 April 2014.|
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