Basking Turtles (Painted, Red-Eared Slider, Red-Bellied Cooter)

Basking Turtles

Did you see that turtle before it slipped into the water? 

Maybe it was too far away, and all that you saw was a round black turtle. Maybe you caught a glimpse of some yellow or red markings on its head and neck. Now you see it swimming at the surface, its head poking out of the water, looking at you and waiting for you to go away before it climbs back out. What was it? 

Our waterways are full of turtles. Several of these species bask in the sun, making them more accessible than when they are swimming or resting under the water. 

Three species account for most of the turtles you see basking in Philadelphia (a few species like map turtles are uncommon, other common species like snapping turtles don’t bask very often)

• Painted Turtle

• Red-Eared Slider

• Red-Bellied Cooter

Description

They look pretty similar at first glance: black, round turtles with a lot of size overlap. Males of all three species are smaller than females, so that a mature male redbelly turtle or red-eared slider can be about the same size as an adult female painted turtle. A lot of the time you might not be able to tell which one you’re looking at, but with a little practice you can learn to tell them apart and study their habits in the city. 

• The painted turtle is a mostly-black turtle with red markings along the edge of the shell. They have red and yellow stripes on their legs and neck, but on a basking turtle you’ll most likely be able to see the yellow stripes on the head. Painted turtles often have noticeable pale lines on their shells where their scutes (the sections of the shell) meet. They are a little flatter than the other basking turtles you are likely to see. These are the smallest of our basking turtles (females top out with 8 inch shells), though a large painted turtle will be the same size as a small individual of the others. 

• The red-bellied cooter has thin yellow stripes on its head and neck and orange or red on the visible parts of the plastron (the bottom of the shell). The carapace (upper shell) usually appears to be an even black, but on close examination you might see bars of reddish color. Older turtles will lose the yellow stripes on the head, making them appear to be solid black. Mature female redbelly turtles are our largest basking turtles, with shells topping a foot long. Their shells look streamlined in profile, though not as flat as the painted turtles’. 

• The red-eared slider usually has a red stripe along the side of the head and yellow stripes along the neck. The shells of basking turtles usually appear to be solid brown or black, though you might notice some yellow lines patterning the carapace as well as yellow color on the plastron. Older turtles can lose the distinctive red stripe. Their shells appear to be comparatively un-streamlined, often with a slightly lumpy appearance. Females can have shells up to about 10 inches long. There is a closely-related yellow-bellied slider that lacks the red head stripe and instead has a thick yellow chinstrap running up its jaw. 

Habitat

Pretty much any body of water in Philadelphia could have any of these three species, though the painted turtles tend to avoid the main sections of our rivers as well as faster-running creeks above the fall line. 

Diet 

All three of these turtles are omnivores. Red-bellied turtles are the most vegetarian of the three, but sliders and painted turtles mostly feed on vegetation as well.

Behavior

These turtles spend their winters dormant at the bottom of our waterways. When it is cold and they are inactive, they are able to get all the oxygen they need through the inner surfaces of their mouths and cloacas (in other words they kind of breathe through their butts). 

As spring warms up, they emerge to bask, feed, and mate. In June and July the females climb out of the water to dig nest holes and lay their eggs. This is a dangerous time for a turtle. They can get killed by cars while crossing the road, and predators such as minks or raccoons can catch them on land. Most nests will be raided by predators such as crows or raccoons. If they avoid detection, in late summer tiny turtles dig their way out and scramble to the water (some will overwinter in the nest and emerge in the spring). Few will survive. They are just the right size to be eaten by everything from crows, to raccoons, and herons.

Spring through fall, all three species will climb out of the water to bask in the sun. Turtles do not generate their own body heat, and so they need to use an external source like the sun to warm up. Basking might also help dry them out and help get rid of parasites. 

Basking Turtles and Humans 

Red-bellied turtles are on the PA threatened species list. Although they have a large range in the Mid-Atlantic, in Pennsylvania they only live in the southeast corner, and much of their habitat has been destroyed by urbanization. 

Red-eared sliders are native to the middle part of North America, including the Mississippi River drainage, but they have been widely introduced as released pets and could out-compete our native red-bellied turtles. 

Observing Basking Turtles

Your best chance to see these turtles is when they are basking. On a sunny day, particularly in the morning, check logs and other objects emerging from the water for turtles that have climbed out to bask. 

Approach basking turtles carefully. They are always on the lookout for potential predators (including humans) and will dive in if you get too close or if they see you looking at them. 

Binoculars will help you get a look from a comfortable distance. You can then approach little by little. After they jump in, wait five or ten minutes. Basking turtles often stay close, swimming at the surface and watching to see if the threat has gone away. They will then climb back out and resume basking. 

You will also have the best luck with the sun at your back. The turtles will not be able to see you as well, and you’ll have good light to make out their markings. 

Living With Turtles

Aquatic turtles benefit from anything we do to improve water quality, including steps you take to green the landscape so that it soaks up water and doesn’t let it rush off into the storm sewers, which contributes to sewage overflows. 

Never release an unowned pet turtle into the wild. Most of them die, unable to find food and learn the landscape well enough to survive the winter and avoid predators. The released pets that survive can introduce diseases into wild turtle populations, and, like red-eared sliders, can out-compete native species. 

Turtles can look like cute pets, particularly the baby red-eared sliders often sold (illegally) with cheap plastic cages, but they are challenging to keep in captivity, particularly as they outgrow their housing. Research any turtle pet carefully before you get one and adopt, don’t shop. There is always someone looking for a new home for a red-eared slider. 

More Resources

Contribute turtle observations to the PA Amphibian and Reptile Survey. 

Learn more about turtles at PA Herps. 

View iNaturalist observations of painted turtles, red-bellied cooters, and red-eared sliders.