Blue Iguana

The blue iguana, indigenous only to Grand Cayman Island, is one of the most endangered reptiles in the world. Faced with habitat loss and predation by feral animals as well as humans, the remnant wild population of blue iguanas survives in fragmented pockets of its original range. Once numbering in the thousands, it had declined to ~150-200 by the mid- 1990’s, and by 2002 the population had plummeted to a remnant of less than 20 wild iguanas. 

Due to the success of captive breeding through the Blue Iguana Recovery Programme, over 900 have been released at the Queen Elizabeth II Botanic Park (QEII), the Salina Reserve, and the Colliers Wilderness Reserve. There are additional iguanas in the captive breeding colony on Grand Cayman and less than 50 everywhere else in the world, for a total global population of a little more than 1,000. The entire wild population now consists of iguanas that were captive bred, captive reared, and/or head-started before release and their offspring. There is excellent survival and successful reproduction of the released animals. 

Since 2001 WCS has provided veterinary support for the recovery program in conjunction with the IUCN Iguana Specialist Group, Cayman Islands Department of the Environment, and the National Trust for the Cayman Islands. Activities have included pre-release evaluations, health assessments, and annual examinations of Grand Cayman iguanas at the QEII breeding facility and free-ranging iguanas. Project accomplishments include determining baseline hematologic and biochemical parameters, enteric culture, parasite screening and treatments, and medical care and necropsy evaluations as necessary. Saint Matthew’s University Veterinary School (SMU) generously provides a laboratory for sample processing. Laboratory processing is conducted on Grand Cayman and samples are also imported to the US for additional analyses.  

Sadly, in recent years feral dog attacks resulted in the deaths of most wild adults in QEII and a disease outbreak also occurred in the wild and captive groups that resulted in some deaths, some sick animals successfully treated, and an unknown number of wild animals affected. Due to concerns about the risk of further introducing the pathogen to the wild population, releases were postponed until the disease and its impact on the wild population was better understood, and new quarantine procedures established. The combination of the dog attacks and the recurrent disease in consecutive years resulted in a serious setback to the wild population’s recovery. A fence was constructed around the park to prevent dogs from entering, and WCS worked with partners to investigate the epidemiology of the infectious disease responsible for the mortalities. 

We found the likely disease causing agent to be a novel Helicobacter species, and noted that most infections occurred shortly after the first rains following seasonal droughts. Further screening detected the same Helicobacter sp. from clinically normal green iguanas sharing the same habitat, suggesting they could be asymptomatic carriers and a potential source of the pathogen.

Banner Blue iguana photo credit: Julie Larsen Maher, WCS

Thumbnail Blue iguana photo credit: Lucy Keatts, WCS

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