Amphibians and Reptiles Invasive Species Pet Trade

Cheap prices lead to more exotic pets in the wild, research finds

This article originally published by  at, republished under Creative Commons licensing (CC BY-ND 4.0).

  • New research shows that exotic amphibians and reptiles sold inexpensively as pets are more likely to end up in the wild, where they can pose problems for native wildlife.
  • The authors of the study believe that many pet owners may not fully understand the responsibility of owning these animals, some of which can grow to large sizes and live for decades.
  • They suggest that limiting the numbers of certain species popular as pets could help limit their often-destructive impact on ecosystems.

Exotic pets that grow to be big adults and are inexpensive to buy are more likely to end up in the wild, according to a recent study.

“It is difficult to unravel why an owner might release their household companion,” ecologist Oliver Stringham of Rutgers University in the United States said in a statement. “Impulsive buying decisions without proper research about care requirements could be a reason.”

Stringham was the lead author of a study published in the Journal of Applied Ecology on Aug. 21.

A vendor’s display of exotic snakes available for purchase at an exotic pet expo. Image © Diane Episcopio.

These non-native animals can struggle, more than their erstwhile owners might think, to make a go of their new environments at times. But more destructively, they can also wipe out the animals they go after as prey, outcompete local species, and bring new and deadly diseases, all of which increase the likelihood of the extinction of native wildlife.

Researchers know that the pet trade is how most reptiles and amphibians from other locales end up wreaking havoc in new habitats. It’s how the Burmese python, a 5.5-meter (18-foot) predator, has taken up residence in Florida’s Everglades National Park in the past few decades, where it’s likely been a part of driving down resident bird and mammal species. Still, the factors that have opened such pipelines have remained a mystery.

Stringham and his colleagues counted more than 1,700 species of reptiles and amphibians that were sold as pets between 1999 and 2016. Lizards topped the list at 739 species, followed by snakes at 490 species. They then looked for which ones most commonly ended up in the wild as non-native species, based on prior research and counts by citizen scientists of these animal invaders. The team also looked for common traits, such as the life expectancy and body mass of different species, that occurred in animals that were more frequently set free.

In addition to affordability, reptiles and amphibians that grow to large sizes and live long lives were more likely to be released. Once these animals have been purchased, exotic pet owners might decide that they’re ill-equipped to handle them, Stringham said.

The green iguana is a common exotic pet that originates from Central and South America. Image © Matthew Sileo.

“They may underestimate the space and costs needed to keep such animals as they grow into adults,” he said. Sentimentality, too, might play a role.

“Understandably, some owners may not wish to euthanise their pet for ethical or emotional attachment reasons,” Stringham said.

He and his colleagues suggest that better-informed pet owners could provide a potential solution. Policies directed at keeping large numbers of animals from setting up shop in a new environment could also help, before the problem becomes insurmountable, ecologist Julie Lockwood, also of Rutgers University, said in the statement.

This Burmese python was captured in Everglades National Park in Florida, where the invasive snakes have established a large breeding population. Image by Susan Jewell/USFWS (Public domain), via Wikimedia Commons.

“Stopping an established species from spreading is often not possible, and if at all, very expensive to eradicate,” Lockwood said.

“When it comes to tackling nature invaders, it is best to take a precautionary approach,” she added. “While it might not be possible to fully prevent the release of exotic pets, reducing the number can be an effective way to prevent new species from becoming established and potentially invasive.”

Banner image of a Burmese python by Susan Jewell/USFWS (Public domain), via Wikimedia Commons


Stringham, O. C., & Lockwood, J. L. (2018). Pet problems: Biological and economic factors that influence the release of alien reptiles and amphibians by pet owners. Journal of Applied Ecology.