Red-eared Slider, Trachemys scripta elegans

Red-eared Slider, Trachemys scripta elegans. Photographs taken within a residential area in South Florida, March 2024. Photographs and identifications courtesy of Faith Hubsch, Fort Lauderdale, Florida.

The Red-eared Slider, Trachemys scripta elegans, is a member of the Emydidae Family of pond and marsh turtles and terrapins. The Emydidae Family consists of fifty species placed into two subfamilies and twelve genera. There are fifteen species in the Trachemys genus. In Spanish, they are referred to as Tortuga de Orejas Rojas. 

The Red-eared Slider is a medium-sized freshwater turtle with a weakly-keeled oval carapace. They have a unique broad stripe of red or orange (rarely yellow) behind each eye, for which they are named after. Their carapace is olive brown with numerous black and yellow vertical lines. Their plastron is yellow and each scute typically has a large dark brown or black blotch. The marginal scutes of their shell are serrated, or slightly forked, in appearance. Their exposed skin is dark green with narrow black and yellow lines running lengthwise along their limbs. Older individuals sometimes display an excess of black pigment that obscures most of the yellow stripes on their shell and skin and the red stripe behind their eye. This condition is known as melanism and is associated with older males. Sexual dimorphism is displayed with males possessing longer forelimb claws, a thicker tail, an anal opening located behind the rim of the carapace, a longer and thinner head, and a more pointed nose. Additionally, males have a concave plastron while females have a flat plastron. However, females often obtain a larger adult size. Males reach a carapace length of up to 20 cm (7.9 inches), while females can attain a carapace length of up to 28 cm (11 inches). Adults can weigh up to 96 oz (6.0 lbs 0 ounces).

Red-eared Sliders are diurnal and aquatic, rarely leaving the water except to bask. They bask on banks, rocks, logs, or other exposed objects, often in large groups, and sometimes stacked on top of one another. They have been observed in every month of the year except for January and can tolerate moderate winters. While they do not hibernate, they become dormant during the cold of winter and enter brumation. This differs from hibernation because they do not fall into deep sleep and still have periods of activity. In warmer parts of their range, they can remain active throughout the year on sunny winter days. During cold winters, they will overwinter at the bottom of a pond or lake. They remain motionless, do not eat or defecate, and breathe less frequently. Red-eared Sliders can survive for weeks at a time without taking in oxygen. Occasionally, they leave the water and walk on land in search of food, a better place to live, a mate, or to lay their eggs in the spring. Sometimes when people see a turtle walking on land they think it is sick or stranded and try to help by picking it up and bringing it home or to a rehabilitation center. Most of the time this harms the turtle by removing it from the wild without reason. If a turtle is found in an obviously dangerous situation it is okay to move it out of harm’s way, but it is best to leave it in a safe place as close as possible to where it was found. 

In their native habitat, Red-eared Sliders mate from March to June. During courtship, the male waves or rapidly vibrates the extra long claws on his forefeet in front of the female’s face. He may also use his claws to “tickle” the face of the female. If the female is uninterested, she will try to avoid the male and swim past him. Often, she will not get very far without running into another male. It is not clear exactly how the female chooses her mate. However, if she is receptive she will allow the male to climb onto her back. Mating occurs while the pair is still in the water and the male uses his forelimbs to hold onto the shell of the female while using his back legs to brace himself. Copulation can last up to fifteen minutes. After mating, the female may store the male’s sperm for an extended period of time before deciding to use it to fertilize her eggs. In fact, she could mate again and use the sperm of multiple males for a single clutch. Using their hind limbs, females dig a nest for their young in open unshaded areas on land in soil that is not muddy. They may move a considerable distance from the water to find a suitable nest site and can sometimes be observed crossing roads during the breeding season. Clutches of two to twenty-five eggs are laid between April and June, and up to five clutches of eggs can be laid per year. Hatchlings emerge after two to three months and will sometimes spend the winter in the nest. Each hatchling breaks open its egg using an egg tooth, which falls out shortly after use. The young are green in color with yellow streaks and several eye-like spots. They take about three weeks to absorb their yolk sac and heal the split on their plastron where the sac was attached. After that, they can enter the water. Young turtles are precocial and no parental care is observed, besides choosing a suitable nesting site. Wild individuals can live up to twenty years of age, and those in captivity can live up to forty years of age. 

Red-eared Sliders are omnivores and their diet includes invertebrates, crustaceans, mollusks, fish, insects, snails, frogs, tadpoles, and aquatic plants. The young are primarily carnivorous, but consume progressively larger amounts of vegetation as they mature. When approached or touched by a potential predator, they will retract their head and use their limbs to tilt their carapace toward the predator. While some individuals remain basking even with the nearby presence of humans, others slide into the water at the first sign of disturbance. They are preyed upon by raccoons, foxes, skunks, and alligators. Large wading birds will also prey upon hatchlings. In some countries they are also consumed by humans. 

Red-eared Sliders may be confused with native turtle species, especially if the red stripe is indistinct due to the animal living in dirty water or is faded due to age. While there are several other native species with markings on their head, none have red stripes. Unlike other species, which tuck their heads in on the side, the Red-eared Slider retracts its head straight back into its shell. This is a very reliable characteristic for distinguishing the Red-eared Slider besides color and pattern. 

From a conservation perspective, the Red-eared Slider is currently considered to be of Least Concern due to their wide distribution, tolerance of a broad range of habitats, and large population size. Individuals and populations can be under varying levels of impact from habitat degradation and loss, road mortality, pollution (particularly pesticides and heavy metals), and collection. These threats collectively are not perceived to endanger the survival of the species. In fact, Red-eared Sliders pose a threat in many parts around the world by competing with native species for food and space. In multiple studies, Red-eared Sliders have shown to be aggressive toward other individuals and even outcompete native species. For instance, competitive interactions have been recorded in parts of Europe between the Red-eared Slider and the endangered European Pond Turtle, Emys orbicularis. This species is included in the IUCN/SSC Invasive Species Specialist Group’s 100 Worst Invasives List. 

The Red-eared Slider is the most popular species of pet turtles. They are farmed in large quantities in the southern USA for the global pet trade. In recent years, they have also been raised for consumption in Asian countries. Nearly all animals in commercial trade, which amounts to approximately six million individuals per year, are produced in near-closed-cycle farms. Wild harvest from native populations has primarily involved adult animals as breeder stock for farms, as well as adults for the domestic and international consumption trade. Females caught in the wild are sold to turtle farms, while surplus males enter the consumption trade. Eggs may also be harvested from the wild.