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Iguana Invasion

Exotic Pets Gone Wild in Florida

and what to do about them

Squirrel Monkey
Squirrel Monkey

Blog (2003-2008)

May 13, 2008: Green Iguanas to cause flooding?*

Green Iguanas may be a species of growing concern in South Florida due to their wildly increasing populations. What most of us are unaware of yet is the infrastructure damage that is being caused by the iguanas’ extensive burrows.

In a study published last month, four scientists point to the environmental damage and the potential costs associated with this invasive species in our state. In examining some of our canals, the biologists found an average of one Green Iguana burrow every sixty square feet. The burrows were as deep as six feet and some were more than seven feet long. So much digging is causing increasing instability and bank erosion. The iguana burrows also can be found in South Florida dikes, levees, and in seawalls along the Intracoastal Waterway.

The scientists conclude that Green Iguana burrows are causing serious damage that may reduce the effectiveness of our flood management systems. The continual and widespread digging by these animals may lead to breaches and flooding in urban and agricultural areas of South Florida. The repair costs from widespread flooding will be exorbitant.

The study suggests that policy makers need to decide to find the funds necessary to fill all the iguana burrows with concrete, cover up the damaged banks with wire mesh, and blow in concrete to seal areas and stabilize structural integrity. The scientists point to the importance of public education so that pet owners realize the dangers of releasing unwanted exotic reptiles in our state. The report strongly suggests a ban on private ownership of unsterilized Green Iguanas.

*Arthur Sementelli, Henry T. Smith, Walter E. Meshaka Jr., and Richard M. Engeman, "Just Green Iguanas? The Associated Costs and Policy Implications of Exotic Invasive Wildlife in South Florida," Public Works Management & Policy, Volume 12, Number 4, April 2008:599-606

April 30, 2008: Iguanas reduced on Gasparilla Island*

According to photographer Michael Oster, the residents of Gasparilla Island have seen moderate success in their 2-year fight to seize control of their home from invading Black Spinytail Iguanas. Islanders report that perhaps 7000 of the estimated 12,000 resident iguanas have been eradicated. That is, trapped and euthanized. The wildlife trappers were funded by a special tax levied by Lee County.

This leaves maybe 5000 more Black Spinytail Iguanas running around the island, breeding more than once a year, eating plants and pooping wildly, freaking out residents and tourists alike. Trappers still have much to do.

Perhaps because the environment has become so hostile, Black Spinytail Iguanas have escaped from Gasparilla onto neighboring islands and the mainland. Sarasota County has received reports of the invasive iguanas in most of their south county parks and in neighborhoods as far north as Siesta Key. In an attempt to keep populations in check, the county traps and removes all invasive iguanas from public lands.

*Michael Oster, "Iguanas Invade Gasparilla Island, Florida! 2008 Update." www.laptopnoise.com

July 18, 2007: Reticulated python eats pet cat*

The news traveled worldwide when a 14-foot Reticulated Python on the loose was captured in central Florida, supposedly after eating a neighborhood cat. The huge snake was live caught and plans were made to transfer it to a zoo.

Reticulated Pythons can eat people too. These aggressive pythons kept as family pets have hurt, and even killed American children. In Southeast Asia where the giant snake is native, people have been swallowed by adult Reticulated Pythons.

In Florida, pythons are an invasive species and are breeding in the wild in suburban neighborhoods.

*"Cat-eating python caught in Florida," Itchmo.com, July 18, 2007

June 8, 2007: Gambian Pouch Rat statewide ban*

The state of Florida has officially banned ownership of Gambian Pouch Rats. Having a pet rat of this African species without a permit is now a misdemeanor, punishable by up to a year in jail or a $1000 fine.

State officials are concerned that the giant rodent, which is breeding in the wild on Grassy Key, will become the newest Florida exotic problem.

The rats are large, omnivorous, and can carry serious diseases.

* "Gambian pouch rat banned from Florida," Associated Press, June 8, 2007

May 25, 2007: Gambian Pouch Rat update*

Federal and Florida state wildlife officials have been attempting for 2 years to eradicate a breeding colony of Gambian Pouch Rats living on Grassy Key. Using 1000 traps baited with poisoned peanut butter, wildlife experts have so far prevented the invasive rats from spreading to other islands in the Keys. However, the raccoon-sized rats are still reproducing in the species’ only breeding population in the United States.

*Angela Harris, "Officials Attempt to Eliminate Extra-Large Rats Proliferating in Florida Keys," Associated Content, May 25, 2007

September 5, 2006: Python vs. gators in Florida Everglades*

While a group of tourists looked on, a 13-foot Burmese Python burst open after attempting to eat a 6-foot American Alligator in Everglades National Park. The horrifying sight included the remains of the snake and the partly digested gator sticking out of the python’s ripped midsection.

Giant exotic snakes have become a major competitor for food and territory in the Everglades, where the American Alligator once ruled. Clashes between the native reptile and the exotic species are on the rise. In February 2004, a python wrapped itself around a gator at the Park. Over a 24 hour period, both animals struggled while visitors watched and filmed the fight. Eventually, the snake broke loose and moved off into the Everglades.

*Victoria Gilman,"Python bursts after eating gator," National Geographic News Online, September 5, 2006; Stefan Lovgren, "Huge, freed pet pythons invade Florida Everglades," National Geographic News Online, June 3, 2004

May 24, 2006: Black Spinytail Iguanas overtake Florida vacation island*

Gasparilla Island is a 7-mile long vacation spot off the southwest coast of Florida. The main town, Boca Grande, calls itself the "Tarpon Capital of the World." This lovely tourist destination has also become the site of the country’s largest invasion of Black Spinytail Iguanas.

These feisty three-foot iguanas do not make good pets. According to town residents, someone dumped a few unpleasant pets back in the 1970s, and the island population slowly grew. During the past few years the numbers exploded. Biologists have estimated a total island population of around 12,000 iguanas, which is about 10 lizards per resident.

Overwhelmed by the poop, the sand dune destabilization, the cement seawall and foundation burrowing, and the sheer numbers, Gasparilla Islanders have agreed to a one-time tax for the income needed to eradicate the invaders. County commissioners are hiring trappers as well as seeking input from area university wildlife biologists.

*Maryann Mott, National Geographic News, May 24, 2006

November 2005: Update on Nile Monitor invasion in southwest Florida*

Scientists from area universities studying the Nile Monitor population in Cape Coral were able to capture and euthanize only 100 of the more than 1000 invasive African lizards. The biologists established the presence of Nile Monitors on neighboring Pine Island and Sanibel Island. Both islands are located more than 2 miles away, requiring a swim across open ocean from Cape Coral. It is unknown whether the lizards actually swam to these islands or are newly released pets.

Multiple sightings in the Orlando area, Miami and Fort Lauderdale, indicate the possibility that the Nile Monitor could become a widespread invasive species in the state of Florida. Eradication may still be possible with adequate funding for a large team of trappers supported by volunteer citizens. Public education is important and wildlife biologists are recommending a ban on the sale of Monitor Lizards as pets in the U.S.

*Todd S. Campbell, "Eradication of Introduced Carnivorous Lizards from Southwest Florida," Final Report to the National Fish and Wildlife Foundation, November 8, 2005

April 2005: Prairie dog bites school teacher*

The Division of Epidemiology and Disease Control of the Palm Beach County Health Department investigated an animal attack on the grounds of a Palm Beach County school. A teacher attempting to keep children away from a loose prairie dog was bitten. The animal, which lived in a burrow on the school grounds, came out of the burrow and bit the teacher.

Prairie dogs can carry serious diseases like monkeypox and tularemia.

* "They’re Not Chip and Dale," Epicenter, Palm Beach County Health Department, April 2005

January 3, 2005: African rats on the loose in Florida Keys*

In 2000, someone let loose 6 or 7, maybe 8, pet Gambian Pouch Rats on Grassy Key, a 1500 acre island some 60 miles north of Key West. Now the first documented breeding population of the African rats is attracting national attention. Florida residents are worried about the huge rats, which can weigh as many as 9 pounds and grow as large as raccoons.

State wildlife experts are seeking funding to embark on an eradication program before the rats increase their range. The nocturnal omnivores can have 5 litters in a single year with as many as 4 babies per litter. Because of their size, the Gambian Pouch Rat can out compete native wildlife for food and territory.

*Jim Epperson, "Large Gambian Rats Worry Florida Officials," Environmental News Network, January 3, 2005

September 26, 2003: Scientists study Nile Monitor invasion in Cape Coral*

A giant African lizard with an appetite for birds, reptiles, and small mammals including domestic pets, has found a new home along the southwest Florida coast. Seven-foot Nile Monitor lizards were first reported on the loose in Cape Coral around 1990, but sightings were rare. By 2002, however, area residents were complaining that the huge carnivores had invaded backyards, sunning themselves along the banks of the city’s many canals.

Scientists estimate there may be more than 1000 Nile Monitors in Cape Coral. A program funded by the National Fish and Wildlife Foundation has brought in a team of scientists from local universities to study these giant lizards and to trap them. The city and county are providing assistance, as are volunteer citizens who report sightings.

Large areas of Cape Coral are undeveloped but devoid of trees in preparation for upcoming city growth. When coupled with the gridwork of canals throughout the city and abundant native wildlife, the environment is attractive to Nile Monitors. Wildlife biologists are concerned about the impact of these exotic reptiles on populations of Burrowing Owls, Gopher Tortoises, and other native animals.

The scientists studying the invasion have recommended the species be outlawed for sale as pets in the state of Florida. If the Nile Monitor moves into Big Cypress National Preserve and the Everglades, native species destruction could prove serious.

*Collette Bancroft, "Enter the Dragons," St. Petersburg Times Online, September 26, 2003

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New book:

Iguana Invasion! Exotic Pets Gone Wild in Florida

by Virginia Aronson and Allyn Szejko

Available at your local bookseller, Amazon.com, Barnes&Noble.com, and Pineapple Press.

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