In the Inner Harbor: Red-Eared Sliders

What do Burmese pythons in Florida, African clawed frogs in California, and red lionfish in the Caribbean have in common?

They're all animals that were first brought to these areas as pets. Irresponsible pet owners released no-longer-wanted animals into the wild where they established populations, often to the detriment of native species.

One of the most common turtles in the Inner Harbor has a bright red stripe on the side of its head. These are red-eared slider turtles native to the Midwestern United States. Today, red-eared sliders are found not only in Baltimore but pretty much everywhere else on Earth. Due to the pet trade, red-eared sliders are the world's most widespread freshwater turtle.

Dime-Store Turtles

In the late 1950s, five-and-dime stores like the national chain Woolworth's sold hatchling red-eared sliders in their pet departments. The tiny turtles were often sold in a clear plastic bowl with a little ramp and plastic palm tree.

About the size of a quarter, these cute, brightly colored baby turtles quickly became popular pets. To meet demand, entrepreneurs opened hundreds of turtle breeding farms in Louisiana, and the dime-store turtle industry was born.

Most of these hatchlings did not live long. Those that survived being shipped, stored and sold quickly outgrew their tiny plastic habitats. Red-eared sliders can grow to 12 inches long and live more than 30 years. When the turtles got too big or outlived their caretakers, many people chose to simply let them go. In Baltimore, countless red-eared sliders were released in places like Lake Roland and Loch Raven Reservoir. Red-eared sliders are so adaptable that they're now well established in almost every county in the state. And that pattern repeated in states all over the U.S. for decades.

In Maryland, red-eared sliders can be spied swimming and basking from March to September. They prefer freshwater habitats but can tolerate low salinity, brackish water and favor the still water of ponds, lakes, reservoirs and slow-moving rivers and streams.

End of an Era

The sale of red-eared slider hatchlings in the U.S. ended in 1975 when the U.S. Food and Drug Administration banned the sale of turtles with shells smaller than 4 inches from head to tail. The government acted because pet hatchings were making their owners sick; turtles and other reptiles commonly harbor salmonella bacteria.

When the large domestic market closed, Louisiana turtle farmers turned to international markets. They started shipping millions of red-eared slider hatchlings to China, Europe and other countries overseas, where things played out similarly to the way they did in the U.S. Red-eared slider populations are now established all over the world, and an estimated 3 to 4 million hatchlings continue to be exported every year.

Do No Harm?

The impact that red-eared sliders have on native turtle populations is not well understood. They do compete with native species for resources, such as food and basking sites, and scientists are researching other effects.

Studies in California and Oregon have shown that red-eared sliders cause population declines in some native turtle species. Research in Europe found that some native turtles living in ponds with red-eared sliders have lower body mass and higher mortality rates than control groups.

There is also evidence, though, that red-eared sliders can positively impact their ecosystems. Because they are so adaptable and hearty, they can fill roles once satisfied by native species that are no longer present. These roles can include dispersing seeds for native plants, accumulating pollutants, breaking down leaf litter, and helping keep invertebrate populations in check. The turtles and their eggs can also serve as important food sources for native predators.

Responsible Pet Ownership

Today, red-eared sliders over 4 inches long are sold legally in Maryland pet shops, and hatchlings are sometimes offered for sale illegally. They're still popular pets, but they're also still frequently given up because of how big they get. As a result, there is a glut of unwanted pet red-eared sliders. Animal rescue groups like the Mid-Atlantic Turtle and Tortoise Society care for these animals with the hope of finding them permanent homes.

Before you get any kind of pet, do your homework and make sure it's a commitment you can keep. If you have a pet you can no longer care for, surrender it responsibly. Releasing pets into the wild is never a good option.