Investigating the Turks & Caicos Rock Iguana.

By Sally C. Dowd

Disguised by the terrain and a rare sliver of shade, a male rock iguana rests under a shrub.

As the heat thickens and the wind subsides, biologist Jimmy Wehsener carefully steps around dozens of cacti on the southern reaches of Big Ambergris Cay, one of hundreds of remote islands scattered in the Atlantic that together form the Turks & Caicos. The flat turquoise sea at his back offers no relief to the dry, rocky ground crunching beneath his boots. Movement draws his eye. Disguised by the terrain and a rare sliver of shade, a male rock iguana bobs its head up and down.
Crouching to its level, Wehsener silently guides a pole towards the wary iguana. With only the slightest brush along rough, layered scales, he fastens the snare over the iguana’s head and lunges forward to grab the squirming reptile. The iguana was not expecting him. This stretch of Big Ambergris Cay remains relatively wild compared to the bungalows and villas that line the oceanfront. Wehsener is here to determine how the divide between natural habitat and palm-lined tourist paradise is shaping the behavior — and future — of the island’s reptilian residents.

The Turks & Caicos rock iguana, Cyclura carinata, is endemic to its namesake islands. They arrived to the island chain thousands of years ago, likely floating in on clumps of vegetation. Staring into their eyes cracks open a time portal to when they were the dominant species on the Islands, living at the edges of wetlands and foraging for fruits on top of untouched hills. Today they can be spotted lounging near crystal-clear resort pools, foraging for discarded food scraps, and scuttling across dirt roads, finding what space they can amidst the Islands’ more recent defining fauna: humans.

Once widespread and abundant across the island chain, these endangered iguanas now occupy just 10% of their historic range. Development projects, cars, and introduced predators, particularly cats and dogs, are large threats hanging over their small triangular heads. 

Before the late 1990s, “there wasn’t a dock, there wasn’t a footpath, there wasn’t a trail,” says Glenn Gerber, a longtime researcher on the island with the San Diego Zoo Wildlife Alliance. As development took ahold, it paved a treacherous path for the island’s ancient inhabitants. With more cars and golf carts flying through the dust, iguanas are increasingly found as roadkill. But perhaps more dangerous to the long-term survival of the species than what happens on the roads is what happens in the resort kitchens.

Crouching to its level, Biologist Jimmy Wehsener silently guides a pole towards the wary iguana.

Turks & Caicos rock iguanas typically feast only on fruits, flowers, and plant leaves, making them critical seed germinators and dispersers for native plants. But, each year, as the white sand beaches sloping toward vibrant coral reefs draw in more people, iguanas branch out from their typical diet. Alongside tourists soaking up the sun and ocean breeze, the rock iguanas indulge in a culinary vacation of their own, snacking on boiled chicken beneath a picnic table or picking through a garbage pile.

This altered feeding behavior comes at a cost, decreasing the overall health and reproductive success of the iguanas. When humans drop food — intentionally or not — more iguanas come to the area in search of scraps. Since iguanas are territorial, increased interactions can lead to more fights. And while fights are largely ritualistic, they still take a toll on the iguanas, draining their energy and leaving behind injuries. 

At the same time as human contact can make them more aggressive with one another, it can also make individual iguanas more docile, “break[ing] down what they would normally be, super wary of potential predators,” Wehsener says, “mak[ing] them more vulnerable to threats.” 

Wehsener is spending five months in paradise as part of his doctoral research in the Blumstein Lab at the University of California, Los Angeles, trucking through rugged scrubland and stealthily lurking around luxurious pools to observe the iguanas. His childhood days spent chasing lizards in the canyons of San Diego have prepared him well for this demanding work. To compare the behavior of rock iguanas at sites with and without human food, he first captures, marks, and tags each iguana so they can be identified throughout their life. Now trackable, he collects data on social interactions, anti-predator response, and wariness.                    

Over the eight days of grueling field work that I spent with Wehsener, we marked a total of 41 adult iguanas, each with a tag, a number etched on in Sharpie, and colored beads tied on to match their number. Head, body, tail, spine, and weight measurements were taken before releasing the iguanas back into the wild to roam free. 

Signs line the dirt roads of Big Ambergris Cay urging people to slow down for the iguanas.

As development and tourism continues to expand in the Turks & Caicos, the rock iguana population doesn’t have to face the threats alone. Wehsener and his colleagues are hard at work studying their populations and collaborating with local officials at the Turks & Caicos Department of Environment and Coastal Resources to better protect the scaly islanders. When he works with Wehsener now, Gerber no longer wades ashore with camping gear as he did in 1995 when he first worked on the island.

“The country definitely puts a big priority on keeping their native animals safe,” Wehsener says. The iguanas are key not only to the environment but the economy, bringing in millions of dollars in tourism revenue each year. On Big Ambergris Cay, officials have banned cats and dogs, implemented strict biosecurity protocols, and replaced cars with golf carts as the main way to cruise around the island. Signs line the dirt roads urging people to slow down for the iguanas. “The solution [to roadkill] is very simple, it’s slowing down”, says Gerber. 

Back at a capture site, Wehsener supports the legs of a writhing iguana, trying to avoid their sharp claws and strong bite. White spines crest its back, spiking above the brownish green-grey skin scarred from fighting. Gripping this lizard is taxing — from human feeding, according to Gerber, many of these iguanas “have doubled in mass.” Wehsener gently places the iguana, now sporting beads and some Sharpie marks, on the ground while curious tourists look on – some of the island’s newest inhabitants watching one of its oldest, both looking to enjoy their own little paradise. 

Sally C. Dowd is a graduate student at the University of North Carolina’s Institute of Marine Sciences studying marine fish and fisheries. In addition to her research, Dowd is a freelance storyteller, turning to writing, photography, and videography to communicate environmental challenges and impactful science. Her work, in and out of the water, is highlighted at www.sallycdowd.com.