Red-Eared Invaders Threaten Native Turtles and Human Health!

Sep 23, 2013

Did you have a pet Red-Eared Slider Turtle (Trachemys scripta elegans) when you were growing up? The distinctive red stripe on the side of the head is attractive and makes it easy to identify them.

The red-eared slider turtle is native in much of the mid- to south-central United States. However, it is an invasive species in California, Oregon, Washington and many other states. The US Geological Survey has mapped areas where it is native and not. Click this link and then scroll down to see the map.

California Department of Fish and Wildlife’s (CDFW’s) Outdoor California magazine reports that non-native pet turtles, like the red-eared slider, are a threat to California’s only native freshwater turtle, the Western Pond Turtle (Emys marmorata). Sliders became a problem because so many owners set them free in a local pond or lake. CDFW recommends removing red-eared slider turtles and other non-native species, like bullfrogs, that eat or compete with native species. They also recommend leaving native western pond turtles in peace. (Be patient if you click on the Outdoor California link; the file downloads slowly because it has lots of information and great photos.)

Why are red-eared sliders such a threat? Oregon Department of Fish and Wildlife reports that they compete with native turtles for food, nesting and basking space, and hiding places. Native turtles have no immunity to parasites and diseases carried by red-eared sliders. Turtles can live more than 20 years, so if you set them free, they will pose a threat for a long time! Dhi (see photo below) has been a pet for 18 years. Her human family decided to keep her, instead of releasing her to a local pond.

Columbia University explains that the red-eared slider plays important roles as both predator and prey in its native range. Because they are aggressive and bold, they compete for both food and space with native turtles, where they are introduced.

Buyer Beware! Small turtles sold as pets also cause Salmonella infections in humans. In May 2013 the federal Centers for Disease Control and Prevention reported a salmonella outbreak that affected 391 people in 40 states and the District of Columbia. 70% of the sick people had been exposed to turtles, and 89% of these people had been exposed to small turtles (shell less than 4 inches long). 30% of sick people with small turtles had bought them from a street vendor and 13% had bought them from a pet store. The CDC notes that in 1975 the US Food and Drug Administration banned sales and distribution of turtles less than 4 inches long, so it’s surprising that they are still being sold.

To download a red-eared slider coloring sheet you can print for kids, click on the link at the bottom of this post.

UC Cooperative Extension Advisors Leigh Johnson, Sabrina Drill and Darren Haver trained 181 employees of public works, parks and a UC Research and Extension Center in Spring 2013 to recognize, report and decontaminate their field gear to avoid spreading aquatic invasive species.