Iguana Foundation

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Anegada Island Iguana

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  • Status: Critically Endangered under IUCN Red List criteria 
  • Major threats: Feral cat and dog predators, competition from free-ranging grazing animals, habitat loss
  • Milestones: 
    • In 1997, a headstart program was initiated on Anegada to allow hatchlings to develop to a size at which they would have greater chance of survival from predation.
    • Since 2003, 125 headstarted iguanas have been repatriated into the wild with a survival rate of over 85%.
  • What still needs to be done:
    • Population control of feral cats and dogs must be achieved for the long-term sustainability of the species.
    • Management of free-ranging grazing animals must be addressed to prevent further habitat damage.
    • Remaining areas of good habitat must be protected.
    • Continued headstarting and monitoring of released and wild animals.

The Anegada Island Iguana is listed as Critically Endangered under IUCN Red List criteria.  Although this species once occupied islands throughout the Puerto Rico Bank, it is now restricted to Anegada, a single island in the British Virgin Islands. The Anegada iguana is the most genetically and morphologically unique species of rock iguana, and among the most endangered.  With fewer than 300 individuals remaining, the Anegada iguana is one of the rarest lizards in the world. Increasing pressures from people and their domestic animals are the primary threats to the Anegada iguana. The primary cause of population decline in this species is the introduction of predators such as feral cats and dogs.  These predators decimate the iguana population by feeding on hatchlings.  The predation rate is so high that hatchlings are never seen outside of hatching season.  Because these hatchlings are consumed before they can reach sexual maturity, the population of Anegada iguanas consists of older individuals with no recruitment in the wild.  Additionally, land clearing has destroyed habitat and feral livestock (including cattle, donkeys, and goats) trample nest sites and severely over-browse native vegetation that iguanas rely on for food.  As a result, the iguana population on Anegada has been declining for decades and now occupies only a small fraction of the island and consists almost entirely of aging adults.

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In 1997, conservation efforts to save this imperiled species increased with the construction of a headstart facility on Anegada.  This intensive effort is expensive but may be the only hope of saving the dwindling population from extinction.  As a part of the headstart program, researchers conduct an extensive survey of the island for nest sites in July.  The sites are marked and during the hatching months, research teams return to collect hatchlings as they emerge.  Hatchlings are then taken to the headstart facility where they are raised in a predator-free area until they reach a size in which they can ward off feral cats.  Since the first headstart release in 2003, with funding assistance from the IIF, 123 Anegada iguanas have been repatriated into the wild.  Released animals are tracked and studied and, since the inception of the headstart program, there has been a survival rate of over 85%.  Headstart animals are now reproducing in the wild.  This program provides the species with a necessary increase in recruitment of young individuals and lowers the chance of immediate extinction. 

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In the future, the project will continue headstarting animals and studying the resident wild population to better document its distribution, size, demography, and ecology. Because full recovery of the Anegada iguana will require habitat protection and eradication of feral mammals, the project will also work toward establishing a national park and controlling mammals, as outlined in the Anegada Iguana Species Recovery Plan.  Additionally, to safeguard against long-term extinction and to increase genetic diversity, several zoos in the United States have begun captive breeding programs for this species. 

The International Iguana Foundation has been providing grants and funding to save this species since the foundation was created.  The IIF grant provided to the Anegada iguana recovery effort this year will help to sustain the headstart program and support further genetic research.   

 The future protection of these magnificent species can be furthered by your donation.

 Please click here to make a contribution to the IIF and help save this species and others from extinction. 

For more information on Anegada iguanas, please go to our species page.

Message from our research team: "Even though the recovery of the Anegada iguana faces many struggles, when we see a wild iguana (or even better a headstarted iguana) in its native habitat displaying natural behaviors, all the frustrations, the mosquito bites, sunburns and scratches are instantly all worth it. It feels good to know we’ve increased the wild population by almost 30% on Anegada. A new camera trapping effort we began in 2010 is supplying even more evidence that the headstarted iguanas are successfully integrating with the wild population. We have a long way to go, but we are on the right path."

The IIF would like to thank Mohamed bin Zayed, George Brown, and Stiftung Artenschutz for funding support.