New ideas needed to control green iguanas

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Adult green iguana (Photo by Mark Orr)

(CNS): An army of around 320 registered loggers has successfully killed nearly 1.35 million invasive green iguanas in the past three years since the project began, but there has been a decline in interest slaughterers despite an increase in the premium. This is largely because the estimated number of iguanas has fallen to around 87,000 from more than 1.32 million when the project started in late 2018. The Environment Ministry says new ideas are now needed to find a long-term solution to this resilient pest.

After a brief Christmas hiatus, felling operations resumed on January 24 with a limited army of around 80 regular fellers and a funding commitment to keep the project going until the end of the next year. According to a report published this month Sway, bimonthly DoE magazine edited by Jane Haakonsson, to date the project has cost C$7.9 million, resulting in the culling of 1,349,919 iguanas since its inception.

The number of green iguanas culled has dropped dramatically in 2021, with just 87,361 killed compared to culling rates of more than 150,000 iguanas per month in the first months of the program. Numbers have declined exponentially as the population declines to an average of around 7,000 per month. Despite increasing the bounty on each iguana from CI$5 to CI$7, hunters are losing interest as the animals become harder to find, which DoE iguana expert Fred Burton predicted when the showdown was first launched.

The DoE said the prime-style approach has likely reached the limit of its effectiveness, which was supported by last year’s annual green iguana survey.

When the culling began, it was estimated that there were around 1.32 million green iguanas on Grand Cayman. After 1.12 million iguanas were killed in the first 14 months of the project, by August 2020 the population had been reduced to just 25,000. The population has rebounded a bit, increasing in the annual survey of August 2021 iguanas at 87,000, not just because of lower fellers or COVID lockdowns, but because of an increasingly alert iguana population.

“The remarkable ability of green iguanas to reproduce… when adequate controls are not in place, is clearly revealed” in the data from this survey, the DoE explained, adding that hatchlings accounted for the majority of slaughtered iguanas arriving. at the resort from August. until December last year.

The DoE said it is committed to ensuring that “the successes, efforts and money invested in
date is not in vain”, and although eradication remains virtually impossible, a long-term response must now be considered to prevent numbers from reaching past levels, which posed a serious threat to the unique natural habitats Islands.

Greens are by no means the only invasive species in the Cayman Islands. In the latest edition of Flicker, the department has revealed details of ongoing biosafety work through a Darwin grant. With C$535,000 in the bag until 2024, the DoE, in partnership with the Department of Agriculture (DoA), the Royal Society for the Protection of Birds (RSPB) and researchers from the University of Aberdeen , establish strong biosecurity and invasive species management protocols.

Dealing with feral cats, chickens and rats and more obscure creatures, such as lobed lake scalemealybug and fruit fly, on the sister islands will be an essential part of the project.

For more details on invasive species control as well as other great features on orchid hunting and the threat to the endangered pygmy blue butterfly due to habitat loss, check out the latest edition of Sway below. Back copies can be found here.


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