Green Iguana control needed

Mr. Jonathan River’s letter about green iguanas, posted Sunday, 5 April, makes some very good points. He asked me for my views.

The ‘Green’ Iguana (actually more properly called the ‘Common Iguana’ and seen in many other colours when adult), was introduced to Grand Cayman rather thoughtlessly in the early 1980s.Their numbers were boosted by escapes and releases from the pet trade, which are still happening today. The Common Iguanas are now breeding in the wild throughout Grand Cayman, and as Mr. Rivers pointed out, their population is going up exponentially.

Common Iguanas belong naturally in Central and South America. Here in Grand Cayman they are an invasive alien species. In their native habitat they are exposed to many different natural predators which (fortunately for all our native wildlife) are not present here. Here in Grand Cayman with only dogs, cats and fast cars to worry about, the Common Iguana’s fecund breeding strategy is missing the corresponding high natural death rate, so their population is expanding out of control. What we are seeing now, is still the beginning of a problem whose future dimensions we can only guess at.

Mr. Rivers is correct that we need a change in the Law – the old Animals Law just states ‘iguanas are protected’ because when it was written, only native iguanas were here. But please let’s not waste time tinkering with that ancient piece of legislation when we have the National Conservation Law ready to solve this problem along with any new one like it. I’m disappointed that legislation still didn’t make it to the House this spring, and I do hope the next government (whoever they may be) will finish what was started more than one electoral cycle ago, and give these islands some modern environmental legislation that will help us to deal with this – and with future problems of this kind.

Changing the law is just the first step. Harder will be to gain consensus on how to control the Common Iguanas once it is legal to do so. There are many who would be ethically and emotionally opposed to a wholesale slaughter, but if we were to capture them live in the thousands, what else could be done with them? Shipping them off island alive would run into overwhelming regulatory and practical barriers.

Mr. Rivers’ analogy with rats is closer than one might think – rats, after all, are just another invasive alien species. Decades of work by pest control professionals and the Department of Environmental Health, can only claim to be moderating the rat population, and eradication is nowhere in anyone’s sights. I fear that pattern might be the best we can expect for Common Iguanas.

I think it would be worth some in-depth research to look for any ‘weak links’ in the Common Iguana life cycle that might suggest control methods less gruesome than an outright cull. Nobody has a happy solution today, but that doesn’t necessarily mean there are no solutions to be had. Whatever we end up doing, we’d better take care that control techniques don’t cross species barriers and impact our critically endangered Grand Cayman Blues, or indeed any of our truly native Caymanian animals and plants. Care will be needed, and science should be our guide.

Fred Burton

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