Baby iguanas, Chinese water dragons, or even ball pythons are undoubtedly cute and tempting to own as pets. But these popular reptiles don’t stay small forever. And according to new research, they are precisely the kind most likely to be released into the wild by humans.
The exotic pet trade is by far the biggest way non-native reptiles and amphibians are introduced into the wild. Imports of Fish and Wildlife-regulated reptiles typically exceed one million individuals annually—and those are just the ones we know about. It’s now clear that the sheer size of the trade plus the pace of pet releases is threatening native ecosystems, as some of these species establish populations and become invasive.
But in order to stop the tide of invasions, we need to know what types of reptiles and amphibians are getting dumped. That’s a puzzle Rutgers University-New Brunswick ecologists Oliver Stringham and Julie Lockwood sought to solve.
In a paper published today in the Journal of Applied Ecology, the researchers compared the attributes of species that had been released in the U.S. to those that hadn’t been released, gathering data on imports and sales from online pet stores, and using a combination of previous research and data from a citizen science project to see which species had actually been introduced to the wild.
The pair documented 1,722 species of reptile and amphibian in the U.S. pet trade between 1999 and 2016, of which 126 were released into the wild. The team found that species that grow to large sizes—especially those that are sold cheaply when young and small—were very likely to be released.
Think boa constrictors, which as babies are an adorable 18 inches long, but can become a 10 foot-long adult in just a few years. Species that live a long time—and thus require potentially costly care for 30+ years in some cases—were also more likely to be released. Unsurprisingly, the most popular species also found their way into the wild more regularly.
“These species are so abundant in the pet market, they’re potentially more likely to be bought by impulsive consumers that haven’t done the proper research about care requirements with some small fraction of these consumers resorting to releasing these pets when they become difficult to care for,” Stringham told Earther.
The consequences of these releases can be catastrophic for native ecosystems. Florida—the world leader in introduced reptiles and amphibians—is a prime example of this, dealing with a scourge of invasive species from Everglades-gobbling Burmese pythons to giant, carnivorous tegu lizards. But it’s not just the invasive species that cause problems.
“Even if released exotic pets fail to become established, they still cause harm to wildlife by spreading new diseases,” Stringham said, noting the deadly, animal trade-driven chytrid fungus plague that has obliterated amphibian populations globally.
By identifying high-risk species, the new study can help direct efforts to keep these releases from happening in the first place. Stringham urges those still interested in owning exotic pets to do thorough research beforehand.
“This means looking up their adult size, lifespan, food and housing requirement and asking if it will be compatible with their lifestyle for the the lifespan of the pet,” he said.