A weeklong green iguana culling trial kicked off this week in a bid to control the population, which has been estimated to have reached half a million on Grand Cayman.
The culling trial, which runs through June 27, was announced on Friday, one day after a group of 18 registered cullers was chosen.
According to the Department of Environment, which organized the cull, the small project will help the government develop a comprehensive and effective plan to tackle the exponentially increasing population of invasive green iguanas in Grand Cayman at the necessary scale.
DoE director Gina Ebanks-Petrie said the department received $200,000 from the Environmental Protection Fund toward developing a green iguana eradication program.
The money will be put toward devising and implementing a strategy to eliminate the threat of the animals. This cull is part of that effort, and the hunters will receive $5 for each iguana brought to the Department of Environment.
Fred Burton, who for many years coordinated the successful Blue Iguana Recovery Programme, is directing the eradication efforts. He noted that the results of the recent green iguana population surveys by DoE research officers Jane Haakensson and Jessica Harvey were “shocking,” and “terrifying.”
“The results are truly appalling,” he said. Ms. Haakensson confirmed that the estimated population of green iguanas in Grand Cayman is about 500,000. “Their population looks to be doubling every 1.5 years,” she said.
This week’s cull follows a much smaller initial effort to eradicate some of the green iguanas by three experienced hunters using licensed air rifles and small teams.
In that recent two-week cull, the three contractors tried to reduce the green iguana density in their designated area by 90 percent. By the end of the effort, more than 4,000 iguanas with a combined weight of about 2 tons, were turned in. The carcasses are taken to the George Town Landfill.
The second trial is intended to test the logistics and effectiveness of involving larger numbers of people in culling over larger areas. The area being targeted encompasses the western part of Grand Cayman, from around Hurley’s to West Bay. The hope is that up to 30,000 iguanas will be caught.
The 18 cullers participating in the trial were drawn from a group who attended a public meeting in 2015 on the future of green iguana control.
The registered cullers are free to involve as many additional people they wish under their primary registration, and Mr. Burton said that the cullers are required to be reasonably humane in their methods, and may use a variety of techniques, ranging from air rifles to nooses to hand capture.
The cullers will need to request permission to enter private property, and the organizers foresee that cullers will be requesting access in many locations. The Department of Environment is asking the public’s cooperation as the green iguanas have become a major public nuisance and a potentially devastating environmental threat.
“It’s hard to grasp the magnitude of the numbers, as the rate of increase was so powerful,” said Mr. Burton.
“If we are going to turn that around, we are talking about very, very large numbers [that will need to be eradicated].” Mr. Burton said the different methods and tactics for culling green iguanas will be analyzed after the cull, with the information used to inform how future efforts will be conducted.
“If we are going to do large numbers low tech, or highly trained cullers going high-tech, for example,” said Mr. Burton. “At the moment, we don’t have enough information to make these decisions.”
From an environmental perspective, Mr. Burton says the sheer number of animals, due in part to their extremely rapid reproduction rate, means they are wreaking environmental damage to the areas they inhabit, devouring plants, defoliating and killing native trees, and stressing and out-competing indigenous animals for food sources.
Mr. Burton said the green iguanas may be exhibiting rapid evolution, as their behavior is not seen in other green iguana populations. For example, they steal eggs from bird nests.
“There is potential for ecosystem change that has a knock-on effect for the entire ecosystem,” said Mr. Burton. “This problem has to be dealt with quickly, but it is going to be tough.”