The blue iguana, scientific name Cyclura lewisi, is a large and endangered species of rock iguana that is endemic to the Cayman Islands in the Caribbean Sea.

Taxonomy and Classification

The blue iguana belongs to the kingdom Animalia, phylum Chordata, class Reptilia, order Squamata, and family Iguanidae. Its taxonomic name is Cyclura lewisi Grant, 1940. It was initially described as a subspecies (Cyclura nubila lewisi) of the Cuban rock iguanas (Cyclura nubila). It was later elevated to species level by Burton in 2004, and this was supported by other researchers.

Morphological Characteristics and Reproduction

The blue iguana is one of the largest rock iguana species in the region. Males of this species are notable for their size, with the largest known males weighing over 10 kilograms. They are known for their long lifespan.

The blue iguana, like all members of the Cyclura genus, is an annual breeder. Reproductively, females lay between 1 and 22 eggs at a time, depending on their age and size. Hatchlings have a high mortality rate due to their vulnerability to natural predators. The estimated generation length for this species is approximately 26 years. While the average lifespan is unknown, it is estimated to exceed 50 years.

Geographic Distribution and Habitat

Cyclura lewisi is endemic to Grand Cayman Island in the Cayman Islands and currently inhabits the North Shore and East End of the island. It is found at elevations between 1 and 6 meters above sea level. Prior to conservation and reintroduction efforts, the species was present in an area of 4 km² in 2002. However, the reintroduction of captive-reared juveniles into protected areas has expanded its range to 15.6 km².

Currently, breeding populations of the species occur only in three protected subpopulations: QE II Botanical Park, Salina Reserve and Colliers Wilderness Reserve. Suitable habitat for the species is considered to be subtropical / tropical dry shrubland.

Threats

The primary threats to the blue iguana are invasive predators, both wild and free-ranging, and habitat loss and conversion. Feral dogs and cats kill adults and juveniles, respectively, and have been observed in all areas where iguanas are present. Norway rats (Rattus norvegicus) can also severely harm hatchlings.

The second major threat, habitat conversion, has arisen when traditional fruit fields were converted into pastures for cattle grazing. This has reduced food resources and suitable habitat. Furthermore, land conversion for housing brings with it rats, cats, and dogs. Deaths of iguanas dispersed from protected areas and collisions with fast-moving vehicles are also documented annually. The presence of the invasive green iguana (Iguana iguana) complicates public awareness efforts to protect the species. There is also a danger that the tradition of consuming iguana meat, introduced by foreign human populations, will lead to the exploitation of native species.

Conservation Efforts

Conservation efforts for Cyclura lewisi include successful breeding in captivity, head-starting of young, and releasing them into protected areas on Grand Cayman. These efforts are led by the Blue Iguana Recovery Program, part of the National Trust for the Cayman Islands. The program's long-term goal is to restore a genetically diverse, self-sustaining population of approximately 1,000 adult iguanas. Feral predator control is a continuing requirement in protected areas where iguanas are present.

The blue iguana is fully protected by local law and is listed on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), effectively keeping it from international trade. Furthermore, the species' potential as a magnet for nature tourism creates the potential to generate sustainable income for conservation efforts.