I have just returned from a great trip to Kingston, Jamaica, to assist in the annual release of Jamaican iguanas. Every year I look forward to this trip; it’s a chance to move my computer “outside,” get my arms scratched by iguanas, and work with a fantastic group of collaborators who are my friends, too. The first few days was spent at the Hope Zoo, where we evaluated the health and growth of all the captive iguanas (202!). Staff members from the Fort Worth Zoo in Texas, the Audubon Zoo in Louisiana, and the Hope Zoo were among the cheerful hands that made this work efficient and lighthearted.
The Jamaican iguana was believed to be extinct since the 1940s, but its existence was confirmed in 1990 when a pig hunter’s dog found an adult iguana. Researchers immediately jumped to attention and discovered that a very small population of iguanas remained in a remote 3.86 square miles (10 square kilometers) of limestone karst, a dry tropical forest in the Hellshire Hills of southern Jamaica.
The greatest threat to the iguana population is from nonnative predators, including Indian mongoose and feral cats, dogs, and pigs. Mongoose are very common throughout Jamaica and are capable of killing iguanas under one kilogram. Another significant threat is illegal tree cutting for use in charcoal production, an activity that has badly degraded approximately one-third of Hellshire’s forest.
The Jamaican Iguana Recovery Group is an organization of Jamaican and international scientists, zoo professionals, and policy makers dedicated to the recovery of the iguana and biodiversity conservation in its Hellshire Hills home. The San Diego Zoo Institute for Conservation Research™ has been a collaborator in this recovery effort since 1993. A central focus of the recovery program involves raising baby iguanas in captivity at the Hope Zoo until they grow large enough to be safe from most predators. We call this strategy a “headstart for survival.” Hellshire Hills is nearly ideal habitat for iguanas, but it has very few open sunny soil patches suitable for nesting. Because of this, most wild females use one of three nesting areas. Hatchlings are collected from these sites at emergence, tagged, and brought to the Hope Zoo. After a few years of growth, the iguanas are returned to their home and released…hopefully to make more babies!
After several super-long days at the Hope Zoo, we calculated that 17 iguanas were ready for release, and we got ready for travel out to the Hellshire Hills. What used to be an all-day excursion, including a four-hour forest hike, the trek to the release site is now much easier with access by boat and only a one-plus hour hike. The core iguana habitat is encircled by a series of traps that keep the iguanas safe from mongoose. As long as the small iguanas stay within this core zone, their chance of survival is good. A team from the University of West Indies in Kingston heads the field research component of this project and monitors the wild iguanas, assesses biodiversity of all herpetofauna, and keeps the mongoose traps operating.
After one last looking over, we all took turns letting the iguanas out of their “repurposed” pillow cases. Most zoo professionals only see these fabulous large lizards in managed care, so to be able to return one to the wild is very rewarding! We released them at the core soil nesting sites so that they will remember where to find them again. With calls of “good luck, make lots of babies,” we headed happily down the hill back to our beach camp.
Since 1996, we have now repatriated 155 iguanas back to their Hellshire home. Though the program has a long road ahead before recovery is assured, field research has documented several milestones including: a greater than three-fold increase in the number of nesting females, successful reproduction among repatriated releases, and long-term survival of hatchlings (and other herpetofauna) within the core mongoose trapping area. Few people can say they have helped bring a species back from the edge of extinction, and I am very proud to be a member of this awesome team. Really, how cool is that?
Tandora Grant is a research coordinator for the San Diego Zoo Institute for Conservation Research.