Reintroduced Iguanas Reproduce in the Wild, Marking Major Conservation Milestone for Rare Species
After 16 years of tireless efforts to save critically endangered Grand Cayman blue iguanas from extinction, captive-reared iguanas that were reintroduced to the wild in 2004 have reproduced on their own for the first time, marking a major conservation milestone for the species.
Since 1990, the San Diego Zoo's center for Conservation and Research for Endangered Species (CRES) has been working closely with the National Trust for the Cayman Islands and international iguana conservation groups to breed, protect, and increase the number of iguanas whose population, according to the most recent survey in 2002, plummeted to less than 25 individuals.
According to CRES Researcher Tandora Grant, the decline of the population is attributed to severe habitat loss and fragmentation due to road and structure development as well as predation by domestic dogs, feral cats, and rats.
A captive breeding program on the Cayman Islands was begun in 1990, but initially breeding success was limited and available release sites did not offer optimal, nor fully protected, habitat for iguanas.
"In 1997, we had raised a few iguanas for a trial release into the semi-protected Queen Elizabeth II Botanic Park," explained Ms. Grant. "Several iguanas established homes in the park, survived, and laid nests; however, hatchlings were never seen because they quickly became victims of abundant feral cats and native snakes."
In recent years, the joint conservation team has fine tuned their husbandry techniques, which include captive breeding, hand-incubating eggs, and "headstarting" juveniles. These strategies have led to a more successful, genetically diverse and abundant captive population. In addition, beginning in 2002, the team excavated eggs from the nests of released female iguanas in the botanic park. These eggs were also hand incubated and the hatchlings were raised to a larger size in the protection of managed care.
"At about two years old the iguanas were large enough to defend themselves from cats, so we released them into the National Trust's Salina Reserve on the north side of the island, where wild iguanas hadn't been seen in more than 20 years," said Ms. Grant. "This month, we have great news of the first evidence of natural reproduction from this group released in 2004. We have high hopes for the future of this wild recolonized subpopulation and will continue to release animals to maximize its founder diversity."
The iguana conservation team plans to track the hatchlings in the Salina Reserve and monitor their survival and growth. Additionally, a second group of captive-bred youngsters were released in the reserve in 2005, bringing the total of released iguanas to 94.
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