Saving the Sister Isle Rock Iguana

a book cover with a photograph of an iguana on the island of Cayman Brac

The Cayman Islands are a system of three islands located south of Cuba: Grand Cayman, Cayman Brac and Little Cayman. I’ve been privileged to work as a citizen scientist for the conservation of the two types of iguanas found there. The most famous is the Blue Iguana found on Grand Cayman, Cyclura lewisi.  Their body color really is sky blue.  They were almost lost to extinction, but some hardworking humans created the Blue Iguana Recovery Programme and their numbers are climbing. This doesn’t mean they are out of danger, but it is a step in the right direction as they say.  You should visit the Blues at the Queen Elizabeth II Botanic Park if you’re ever on Grand Cayman.

I am more interested in the lesser known Sister Island Rock Iguanas (SIRI), Cyclura nubila caymanensis.  They’ve also been called the Lesser Caymans Iguana but there is nothing lesser about them. They’re said to be a subspecies of the Cuban Rock Iguana, Cyclura nubilaThey are endemic to only the Sister Islands.

Little Cayman has a fairly large population of iguanas, but Cayman Brac’s iguanas are having a tough time surviving.  Along with the usual human-caused problems, habitat destruction and feral pets, the iguanas on Brac have a high road mortality. Because the iguanas enjoy the warm, smooth roads, they are at risk for being run over by cars. Sadly, over the last few years many of the local iguanas have died this way.

My friend Bonnie Scott Edwards, who lives on the Brac, asked me to help her spread the word about the iguanas being needlessly killed. I’m always willing to help with causes like this. She had some terrific photos of iguanas both living and dead – I prefer the live ones myself. Then my friend, Anderson, who does great drawings for my books, filled in the blanks with his illustrations for my book, Silent Rocks. The book turned out great and I hope it helps not only to educate people but also tugs at their consciences. Every time an iguana is senselessly killed, a part of the future dies.

Some people wonder about the value of the iguanas. Did you know that many plants require the help of the iguanas to germinate and grow? When seeds pass through the iguana after being eaten, they germinate faster. The iguanas also help with the seed dispersal because it’s hard to make such large, active lizards stay in one place. They go up the bluff, then down the bluff, then up the bluff, then down–well, you get the idea.

However, not just any iguana will do. Many areas have introduced the Green Iguana, Iguana iguana, into rock iguana territories. Some research suggests that seeds passing through the Green’s gut does not help the plants in rock iguana territories. Only the correct iguana will do. This makes sense, since many of the plants evolved along with the iguanas. More studies are being done.

I’m helping Bonnie with her mission to save her Brac iguanas. They’ve put up some signs reminding people that there are iguanas on the road, so they’ll slow down and maybe even stop texting. Bonnie also tells them about the dangers of letting their pets run loose. Iguanas didn’t evolve with large mammalian predators, so they don’t know that dogs and cats are dangerous. They think they are just friends they haven’t met yet. It is so sad when they realize their mistake too late.

Then there’s the habitat destruction, with the iguanas’ dens being buried during construction. And lastly, are the poisons. Some rat poisons are the same color as the iguanas’ favorite flowers. Of course, the rats and mice were introduced by people, too. So many dangers have come along with people.

The population of the endemic Sister Island Rock Iguana (Cyclura nubila caymanensis) on Cayman Brac is in serious decline. These vegetarian lizards are an important part of the island’s ecosystem. The reduction in population is the result of human activity on their habitat and the threats can only be eliminated by human action.

But people can also solve these problems and I’m hoping the people on Brac working to help the iguanas do succeed. Like the blue iguanas on Grand Cayman, the Brac rock iguanas can be brought back from the brink of extinction.

I wrote a book about this important issue. It’s called Silent Rocks. Bonnie’s photos of the iguanas of Cayman Brac are wonderful.

Which Iguana is Which?

Iguanas are an important part of my life. They are featured in the children’s book I wrote called The Dragon of Nani Cave, which is an adventure tale starring curly-tail lizards ,Gene and Bony, who live on Cayman Brac. I weave the science of the island into the story, because science can be fun!

I am also the author of the book Silent Rocks, which is for all ages, and is about how to save the endangered Rock Iguana of Cayman Brac.

Most iguanas are found in the Americas and on Caribbean islands. They are grouped into three types: iguanas like the common green iguana, rock iguanas and spiny-tail iguanas. Each has evolved to thrive in their native environment. Unfortunately, through international commerce, the green iguana, Iguana iguana, has been introduced into ecosystems where they don’t belong.

Have you ever wondered how to tell iguanas apart? Being able to accurately identify iguana species is important to telling the difference between native iguanas and the invasive green iguanas. I have nothing against green iguanas. I’ve known many through the years as pets and when I operated an iguana rescue. Unfortunately, they are damaging the ecosystems and out-competing the native species.

Green iguanas live in an environment with many predators. So, greens lay many eggs and adapt to many foods. They have that in common with rock iguanas, who are also opportunistic eaters. (Sadly, they’ll even eat human food.)

But back to the telling iguanas apart. There are now booklets that show the physical differences. Rock iguanas don’t have the gorgeous subtympanic scale–that’s the big scale under the ear–that the green iguanas have. My mother called it the ‘jewel.’ It is lovely, in many pretty colors. No other iguanas have that scale. Greens also have little points on their dewlaps. A dewlap is the piece of skin under the chin. ( Oooh, that rhymes.) The greens have smooth, striped tails. Other iguanas have less striped tails.  Rock iguanas have that nice ribbing along the tail, while spiny-tails have keeled scales on their tail giving them a rough appearance.

I wanted to produce an item that would aid people in correctly identifying iguanas, something that was convenient to carry and interesting to look at. I was asked to make the text rhyme because this helps in memorizing the facts.  Anderson Atlas, John Binns and I have prepared these conveniently-sized booklets that people can carry around with them.

Check them out –they’re free. Please use the contact form on the Contact Page to request copies of these brochures for iguana identification.