Conservation of Critically Endangered Caribbean Rock Iguanas
Young iguanas are raised in a safe, captive environment until they are large enough to defend themselves.
As the largest extant land vertebrates native to many Caribbean islands, rock iguanas have proven to be effective flagship species for conservation efforts throughout the West Indies. Conservation Research Fellow Dr. Glenn Gerber continues to work with the Applied Conservation Division of the San Diego Zoo's CRES to conserve two critically endangered species of rock iguana: the Turks and Caicos iguana Cyclura carinata and the Anegada iguana Cyclura pinguis.
The Turks and Caicos iguana has been extirpated from most islands in the Turks and Caicos and is now restricted to less than five percent of its historical range. In response to threats from introduced predators and human development, iguanas were translocated in 2002 and 2003 from two large but threatened island populations to four small, protected islands with suitable habitat that lacked extant iguana populations. To study translocation success, source and translocated populations are monitored two to three times annually for growth and reproduction, levels of stress hormones, blood chemistries, and the nutritional composition of food plants. This collaborative effort involves the CRES divisions of Applied Conservation, Reproducitve Physiology, and Pathology, the San Diego Zoo's Nutrition Department, the Turks and Caicos National Trust, and the Department of Environment and Coastal Resources.
Translocated iguanas quickly adapted to their new island homes and successful reproduction has occurred on all translocation islands each year. Iguanas hatched on translocation islands have grown two to four times faster than juveniles the same age on source islands. This has resulted in a significant reduction in age at maturity on translocation islands (2 to 4 years) relative to source islands (6 to 7 years), and it is anticipated that the first cohort of iguanas hatched on the translocation islands will begin to reproduce in 2005.
Significant progress was also made in the conservation of the Anegada iguana, native to the small island of Anegada in the British Virgin Islands. Once widespread, the current population is confined to a small portion of the island and consists of only a few hundred aging adults. Extremely high mortality of juvenile iguanas is due to predation by introduced cats. To combat this threat until feral cats can be controlled, juvenile iguanas have been collected as they emerge from nests and then they are transferred to a headstart facility on Anegada. Here they are captive reared in a safe environment until they are large enough to survive in the wild. This collaborative project involves CRES's Applied Conservation and Genetics divisions, the Dallas Zoo, the Forth Worth Zoo, and the British Virgin Islands National Parks Trust. Almost 50 headstarted iguanas have been released so far, with an 87 percent survival rate.This program has bolstered recruitment into the wild population, thereby reducing the species' risk of extinction.
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Involving the Public in Protecting Critically Endangered Caribbean Rock Iguanas
