Reptiles
Red-eared Slider
Trachemys scripta elegans · also called red-eared slider, red-eared terrapin, water slider
The red-eared slider is the small green turtle with a red streak behind each eye that has been sold in pet shops for seventy years. Almost every one of those turtles outgrew its tank and outlived its owner’s interest — and enough of them ended up in ponds and rivers to make the species one of the most invasive reptiles on Earth.
Overview
Red-eared sliders are native to the Mississippi basin and Gulf coast of the US and northeastern Mexico, in still and slow fresh water — ponds, marshes, ditches, slow rivers — with plenty of basking sites and soft bottoms. They are strong swimmers, omnivorous (more carnivorous as hatchlings, more herbivorous as adults), and spend hours a day basking in the sun, which they need for shell and bone health.
The pet, and the fallout
The slider became the world’s most popular pet turtle because hatchlings are tiny, cheap, and farmed in bulk. But a hatchling grows into a 20-centimetre turtle that lives 30 years and needs a large heated, filtered, UV-lit tank. Owners lose interest, and instead of surrendering the turtle, release it — seeding breeding feral populations on every inhabited continent. The slider is on the list of the world’s 100 worst invasive species.
Harm to native turtles
Feral sliders outcompete native freshwater turtles for basking sites and food, crowding smaller species off logs. They also grow faster, breed earlier, lay more eggs, and tolerate poor water better. The European pond turtle and others have declined where sliders are common.
Salmonella
Small pet turtles can carry Salmonella, which led the US to ban the sale of turtles under 10 cm in 1975 after thousands of child infections. Turtles should be kept away from young children, and tanks never cleaned in a kitchen sink.
Status
The red-eared slider is Least Concern and increasing — abundant at home and, unfortunately, abroad. A turtle you cannot keep should go to a rescue or herp society, never a local waterway.
Red-eared Slider: common questions
Why are red-eared sliders such a common pet, and why is that a problem?
They became popular because hatchlings are small, cheap, hardy, active, and readily bred in large numbers on farms, mostly in the southern United States. Tens of millions have been sold worldwide since the 1950s. The problem is what happens next — the "cute" 4-centimetre hatchling grows into a 20-centimetre turtle that lives 30 years, needs a large tank with heating, filtration, UV lighting, and a big dry basking area, and produces a lot of waste. Owners routinely lose interest or become unable to house the turtle, and instead of surrendering it, many release it into the nearest pond, lake, or river. This has seeded breeding feral populations on every inhabited continent.
How does the red-eared slider harm native turtles?
Where it establishes, it competes directly with native freshwater turtles for the two things that matter most — basking sites and food. Red-eared sliders are aggressive baskers and will crowd smaller native species off logs and rocks, and a turtle that cannot bask enough suffers poor shell and bone health and lower reproduction. They also grow faster, mature earlier, lay more eggs, and tolerate degraded water better than many natives. In Europe, the native European pond turtle and Spanish terrapin have declined where sliders are common; similar effects are documented in Japan, Australia, and elsewhere. Sliders can also introduce parasites and diseases.
Do pet turtles carry salmonella?
They can, and this was the reason the US Food and Drug Administration banned the commercial sale of turtles with a shell length under 10 centimetres in 1975. Small turtles are handled — especially by children, who may put them or their hands in their mouths — and reptiles frequently carry Salmonella bacteria in their gut without appearing sick, shedding them into the water and onto surfaces. Thousands of human infections a year in the US were linked to small pet turtles before the ban. The bacteria are not eliminated by the turtle being "clean"; the safe practices are to keep turtles out of homes with young children or immunocompromised people, never clean tanks in a kitchen sink, and wash hands thoroughly after any contact.
What should you do with a red-eared slider you can no longer keep?
Not release it — that is illegal in many places and ecologically damaging. Contact a reptile rescue, a herpetological society, a nature centre, or the shop or breeder; some will take turtles back or rehome them. Rehoming to another responsible keeper with adequate space is ideal. In regions where the slider is already a widespread invasive species, wildlife authorities may accept surrendered animals for humane euthanasia. The broader lesson, repeated by conservation agencies worldwide, is to think hard before acquiring any long-lived reptile, and never to solve the problem by putting it in a local waterway.