Innocuous Invaders

By: Zippy Spanjer  |  December 22, 2020

By Zippy Spanjer

Shield-back stink bugs. Kudzu. Sail-finned catfish. The terrifying murder hornet (Vespa mandarinia). And now, tegus. Invasive species have been a problem for centuries, and are often the fault of human species relocation. 

The Argentine black and white tegu is a medium-sized lizard native to — you guessed it —  Argentina. Fully grown, they can be 3-5 feet long. They are omnivores, happy to eat leaves, insects, and eggs. And this is where the trouble emerges.

Tegus were first found in the wild in Florida in 2012. The lizards are popular in the exotic pet industry, but some people decided to release their pets into the wild instead of rehoming them. The tegus are thriving, which is positive for them, but they are eating the eggs of vulnerable species, disrupting the ecosystem.

A species is considered invasive if it is not native to the area it inhabits. So, in a sense, we humans are an invasive species. If the new species can fit into an ecological niche in its new environment, its invasive status will not necessarily be a problem. For example, the peregrine falcon is an invasive species in New York City. After the species was nearly driven to extinction by pesticide use in the 1980s, they were reintroduced to the city, where they roost in skyscrapers and help keep the pigeon and rat populations under control.

The real concern emerges when the invasive species disrupt the local ecosystem. This tends to happen if the invasive species has no predators in the new area, or if the new species is itself an apex predator. In such cases, there are many ways an invasive species can impact their environment. Some species, like feral cats, multiply out of control and eat prey that is necessary for the survival of native species.

Once an invasive species gains a foothold in a new environment, it can be hard to remove. In the case of tegus, the current system relies on people reporting tegu sightings, whereupon a team is sent out to humanely capture the lizard. The tegu will be rehabilitated and likely rehomed as a pet. This is a time-consuming and often inefficient process.

So, the next time you’re thinking of releasing your exotic pet into the wild, don’t. The consequences could be greater than you imagine.