Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 31, Number 1;   January, 2004

The Ecological Impact of The Introduction of the Spiny-Tailed Iguanas On Keewaydin Island, Florida

by Eric Staats, December 25, 2003, Naples News

U.S. Fish and Wildlife Service biologist Dennis Giardina got special permission from Rookery Bay National Estuarine Research Reserve to go hunting for the wily reptiles and bagged three of them in September.

He shipped their frozen carcasses, along with another 12 dead iguanas that had been stored in a freezer at the reserve as far back as 1998, to the University of Florida for an analysis of their stomach contents. The carcasses are soaking in preservative at a university lab, waiting for their turn to go under the knife.

"I even volunteered to go up there and help them do it," Giardina said. Sorting through the remains of an iguana's last meals could take some time, but a herpetologist on the case in Gainesville couldn't say exactly how long. It all depends on what they find.

University of Florida herpetologist Kenneth Krysko said not only will he be looking for animals but also plants and insects to get a handle on the iguanas' tastes. "When things are mostly digested or even partly digested, it gets pretty tough," he said.

The origin of the Keewaydin iguanas remains a mystery. The leading theory is that someone released the iguanas on the island in the early 1990s. Some say a resident wanted to give the place a more tropical feel. Others suspect a pet store going out of business. Releasing a non-native species into the wild is a crime against nature. It is a second-degree misdemeanor that carries a maximum penalty of 60 days in jail and a $500 fine.

Reports from residents of dwindling gopher tortoise populations renewed interest in whether the iguanas are damaging the island's ecosystem. The creatures have been spotted on surrounding islands and even in back yards in downtown Naples.

Giardina's work on Keewaydin is set to continue in 2004 with another iguana hunt, this one coinciding with the peak of potential prey species' nesting season. As the search for answers on Keewaydin continues, a new non-native threat could be on its way, this time from East Naples. Giardina said he is checking out reports that someone has released Nile monitor lizards on a wooded lot on a side street off Bayshore Drive, possibly to breed the animals and sell their offspring. If they spread into natural areas, the lizards could pose a more serious problem to native wildlife than the iguanas on Keewaydin, Giardina said. "It makes the spiny-tailed iguana look insignificant by comparison, a walk in the park," he said.