On June 10th, the Massachusetts Environmental Police received a strange call. “We got a call to our dispatch from someone who claimed there was a three-foot lizard in their backyard in Chicopee, Massachusetts," recalls Massachusetts Environmental Police Lt. Tara Carlow.
When officers arrived on the scene, they found a disgruntled homeowner and a fully-grown Argentine tegu. Also called black-and-white tegus, these exotic lizards can reach over four feet in length and are native to rainforests and savannas across South America. Still, Carlow wasn’t surprised one turned up in Chicopee.
“We get these types of calls at least once a year,” she says.
In the state of Massachusetts, Argentine tegus are widely sold, and citizens do not need a permit to own one. Tegus are skilled escape artists, Carlow says, and this is hardly the first time one has gotten loose in Massachusetts.
People often purchase exotic pets without understanding what they're getting themselves into, Carlow says. Tegus, pythons, parrots, sugar gliders, and many other animals sold as exotic pets can live for upward of 20 years, nearly twice as long as the average dog. Caring for a long-lived exotic pet is an expensive and, in some cases, risky endeavor—because exotic pets are largely undomesticated, their behavior can be unpredictable. In the United States, at least 300 people have been attacked by an exotic pet since 1990, according to the nonprofit Born Free USA. (Read about how young collectors in China are fueling a boom in ultra-exotic pets.)
It is for these reasons, Carlow says, that escapes—and even intentional releases of exotic pets—are not uncommon.
When this happens, the fallout can be catastrophic. If the animal doesn’t die as a result of predation, exposure, or starvation, it may find a mate, proliferate, and become an invasive species.
The exotic pet trade now ranks among the primary causes of the spread of invasive species, according to a new academic review published last month in the journal Frontiers in Ecology and the Environment. The review finds that the exotic pet trade has led to the establishment of hundreds of invasive species and is poised to contribute to the establishment of even more.
“I don’t think most of us fully grasped how expansive the trade has become,” said lead author Julie Lockwood, professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University, in a statement. “The volume of vertebrate animals that are traded worldwide is shocking, even to relatively seasoned invasion biologists.”
Invasive species are the second largest driver of biodiversity loss worldwide. They’re estimated to cost the U.S. some $120 billion a year, and more than 40 percent of species listed as threatened or endangered in the U.S. reached that status because of invasive species. Invasive species alter habitats, break up food chains, eat up prey populations, and reduce predator populations.
Pets to pests
The exotic pet trade is a multibillion-dollar industry involving tens of millions of individual animals from thousands of species, including reptiles, amphibians, fish, birds, and mammals. It has become significantly more widespread over the past few decades, in part because of the rise of non-traditional marketplaces, such as websites, trade shows, and social media. Most research into the trade has been on its role in the spread of disease or loss of biodiversity, so not much attention has been given to its role in the proliferation of invasive species, the authors write.
“Key to addressing the invasion threat of exotic pets is learning more about the socioeconomic forces that drive the massive growth in the exotic pet market,” the study says, as well as understanding why people release their exotic pets into the wild.
How and why exotic pets are introduced into foreign environments is not well understood, says Mark Hoddle, director of the Center for Invasive Species Research at the University of California, Riverside, who was not involved in the study.
“Sometimes pets escape from their enclosures. Other times people get tired of looking after them and just let them go,” he says. People also deliberately release exotic animals for religious reasons and to make their surroundings “more interesting,” he says. (Learn how a dozen Asian monkeys took over a state park in Florida.)
Stopping the spread
“The best way to address the spread of any animal brought in through the pet trade is through education, early detection, and rapid response,” says Christina Romagosa, an invasive species biologist with the University of Florida's Department of Wildlife Ecology and Conservation and co-author of the study.
Unfortunately, in Florida, the tegu has already established itself. They regularly raid the nests of Florida’s egg-laying species, including the threatened gopher tortoise, a keystone species whose burrows provide homes for hundreds of other animals. It’s just the latest invasive species to wreak havoc on the state’s native birds and reptiles. Florida’s infamous Burmese pythons, which became fully established as an invasive species in the state around 2000, have been blamed for reducing mammalian diversity in the state. Similarly, red lionfish, highly venomous aquarium fish introduced into Florida waters in the late 1980s, have significantly diminished the abundance and diversity of marine life on the state’s coral reefs. (Read more: Burmese pythons eating through Everglades mammals at an "astonishing rate.")
“Wherever they are, there are definitely less fish in that area—especially fish that are good to spear,” spearfisherman Jarrad Thomason previously told National Geographic.
Romagosa emphasizes that education is particularly important. She’s found that consumers who know exactly what they’re signing up for when they purchase an exotic pet are less likely to release them. Equally important, she says, is more research.
"We simply do not have a lot of information on what factors lead to a species being incorporated into the [pet] trade in the first place, or what factors lead to escape or release," Lockwood says. "Without this information, it is very difficult to pinpoint policy directives so that people can still enjoy owning and interacting with exotic pets while reducing the chances that the trade will generate more harmful invasive species."
As for how—or why—that tegu in Massachusetts got out, we still don’t know. The exotic escapee is currently living in a reptile care facility while police try to find his owner.