Pet Problems

1 small animal reveals how the pet trade hurts ecosystems

Approximately 12.6 percent of animals in the global pet market are invasive species.

Originally Published: 
Getty Images

For four years, a “mystery monkey” traipsed around Tampa and St. Petersburg, Florida, bewildering residents and frustrating the Florida Fish and Wildlife Conservation Commission’s attempt to capture the rogue primate.

The monkey — a rhesus macaque, native to Asia — was eventually captured after “a three-hour stakeout” in 2012. The saga of the strange Florida monkey seemingly came to an end — until another macaque was found touring Tampa in 2016.

Rhesus monkeys on the loose have been a problem in Florida since the 1930s when a manager of a glass-bottom boat operation allegedly released six to attract tourists. They’ve destroyed mangroves, causing vegetation loss and shoreline erosion. They’re an invasive species, and invasive species harm habitats.

New research illuminates how invasive species like the rhesus monkey continue to travel the world through the global pet trade, endangering ecosystems in the process. The problem, the researchers suggest, goes beyond more stereotypical exotic animals turned pets like monkeys.

To determine the significance of this issue, the team turned to an unlikely pet traveling the world: the ant.

What’s new — The study suggests the global pet industry is a significant contributor to the dominance of invasive species across Earth. This finding was published Monday in the journal Proceedings of the National Academy of Sciences.

Co-author Jérôme Gippet, a researcher at the University of Lausanne in Switzerland, tells Inverse the pet trade not only creates opportunities for “biological invasions,” it specifically favors species that are invasive. Overall, his team’s work suggests invasive species are overrepresented in trade across animals — including mammals, birds, reptiles, amphibians, and fish.

How they did it — Using data from existing databases and scientific literature, the researchers compiled a list of commonly traded pets.

Then, drawing from the Global Register of Introduced and Invasive Species, the scientist determined which animals from the global pet trade were invasive species.

Out of a dataset of 7,522 vertebrate species in the pet trade, researchers found that 12.6 percent of animals in the global pet market were invasive species.

They also found, on average, invasive species were 7.4 times more frequently observed in the global pet trade than they were in their natural environments.

These nonnative animals were especially represented in the trade of amphibians and fish, but the scientists found high degrees of invasive species across all the major vertebrate types.

A figure from the study showing the representation of different kinds of invasive animals in the global pet trade. The chart shows a high degree of invasive reptiles and amphibians in the U.S.

Digging into the details — However, the researchers still had two burning questions:

  • Did animals simply become more common in the pet trade as they grew more invasive in real life?
  • Or did being invasive species actively help these animals succeed on the global commercial market?

Researchers determined a clever way to resolve their “chicken-or-egg” dilemma: by examining an unexpected, yet formidable new competitor in the global pet trade. Enter, ants.

Although we might not think of ants as “pets,” the study authors argue these insects are slowly becoming more of a presence in the global pet trade. Furthermore, compared to larger animals, “a colony consisting of a queen, a few workers, and some brood can easily be delivered through standard mail,” the researchers write.

Gippet tells Inverse several invasive ant species are becoming more popular in the global pet trade, including tropical fire ants (Solenopsis geminata) and crazy ants (Paratrechina longicornis). Surprisingly, even common black garden ants (Lasius niger) can become devastating invasive species when transported far outside their native range.

“Because these species have less [or unknown] negative impacts than famous invaders, people might not realize they could become invasive if kept outside their native range,” Gippet says.

Critically, it takes several years for an invasive species to become fully entrenched in its new habitat. Ants have only started to appear on the global pet trade since the 2000s, so the study team hypothesized it was unlikely they already dominated new habitats.

However, after analyzing several online shops selling ants across the world, they found invasive ant species appear in the global pet trade at a rate that’s 6.6 times higher than their natural occurrence in the wild.

Even garden-variety ants can become invasive species when transported far outside their native habitat range, say the researchers.


Why it matters — Two specific factors help invasive species — like the ants — dominate the global pet trade:

  • A large habitat range
  • Good adaptability to a variety of habitats

Previous research suggests 53 percent of invasive vertebrate species in the world have been introduced by the pet trade.

As the multi-billion-dollar global pet trade continues to flourish, the study authors suggest the number of invasive species in natural environments will likely skyrocket in the coming years — especially as we look to new parts of the globe for uncommon animals.

Naturally, invasive pets venture into the wild in their new habitats — either by escaping or because their owners release them — where they wreak havoc on local ecosystems.

This team predicts the problem will lead to a positive-feedback loop whereby invasive species become introduced to new locales again and again — a phenomenon known as the bridgehead effect.

But there’s also still a chance we can end this negative cycle, the researchers argue.

What’s next — Gippet says there’s a moral obligation to end the spread of invasive species via the global pet trade.

“Our findings highlight that regulating the pet trade is not only about protecting endangered animals from overexploitation, but also about protecting ecosystems — and human populations — from potentially harmful invaders,” Gippet says.

The researchers call for greater urgency in the current regulation. For example, the scientists note that existing treaties on endangered species don’t actually protect the majority of animals from invasive species.

They’d also like to further examine the differences in invasive species across animal groups in the pet trade, such as birds or mammals. More quantitative data, along with better regulations, could help curb the invasive species problem in the pet trade — before it’s too late.

“I hope that our findings will help to make better decisions on how to regulate the global pet trade in the future,” Gippet says.

Abstract: The pet trade has become a multibillion-dollar global business, with tens of millions of animals traded annually. Pets are sometimes released by their owners or escape, and can become introduced outside of their native range, threatening biodiversity, agriculture, and health. So far, a comprehensive analysis of invasive species traded as pets is lacking. Here, using a unique dataset of 7,522 traded vertebrate species, we show that invasive species are strongly overrepresented in trade across mammals, birds, reptiles, amphibians, and fish. However, it is unclear whether this occurs because, over time, pet species had more opportunities to become invasive, or because invasive species have a greater commercial success. To test this, we focused on the emergent pet trade in ants, which is too recent to be responsible for any invasions so far. Nevertheless, invasive ants were similarly overrepresented, demonstrating that the pet trade specifically favors invasive species. We show that ant species with the greatest commercial success tend to have larger spatial distributions and more generalist habitat requirements, both of which are also associated with invasiveness. Our findings call for an in-creased risk awareness regarding the international trade of wildlife species as pets.

This article was originally published on

Related Tags