Yesterday afternoon I’d put Raven out on her tie-out in the yard, and was sitting inside at my computer doing some work. Raven will occasionally bark at random things if she’s feeling bored – a stray flowerpot, a broom propped against the house, other things that I can’t see. She’s got a particular type of bark that goes with those objects, playful. But yesterday she started barking something different, very much alarmed and uncertain, something she almost never does. So I went out to investigate.
I noticed some movement in the long grass at the edge of the lawn, which I took at first to be a snake, so I returned inside to get my camera. When I approached closer, to take a photo, I realized it wasn’t a snake, after all, but rather a turtle. I reached in and pulled it out of the grass for a better look. It was a Painted Turtle, Chrysemys picta, and a good-sized one with a shell 15cm (6″) long.
I presume that she was wandering about looking for a sandy spot to lay her eggs, since this is about the time of year they would be doing so. If that were the case, then this would be a female turtle. The females don’t reach sexual maturity until at least 5 years of age, sometimes not until 7 or even older, while males are ready to mate at 2-3 years. That’s a long time to have to avoid predators and cars. Dan thought he saw another one in the side yard near where the soil was recently disturbed to have the septic tank pumped last week. That’d be a great spot for a turtle to lay eggs, so I’ll have to check for any signs of digging. The nests are only about 10-12cm (4-5″) deep, and the female lays only a relatively modest 4-15 eggs. However, she may build up to five nests in a season.
There are two ways to determine the sex of the turtle. One is by the placement of the cloaca on the underside of the tail. In females, the cloaca is close to the body, while in males it’s further down the tail. This confirms this individual as a female. Also, the shape of the shell above the tail is helpful: in females it’s relatively straight, while in males it’s notched above the tail. The reason for both of these differences has to do with how turtles mate. Sex in plated body armour is not easy, and takes a bit of careful manoeuvering. The male climbs onto the back of the female with his forefeet so that his tail is approximately aligned with the female’s, and then curves his tail underneath so their cloacas meet. The notch is so that when his shell is tipped backwards it’s not cutting into his tail.
Even the tail gets tucked away when the turtle pulls itself into its shell. Really, when they “retract” their body it isn’t all that different from you pulling your knees and arms to your chest to form a tight ball, except that the turtle has a wide, hard shell overhanging on each side. A turtle’s shell is actually modified bone; the back is modified ribs, broadened and flattened to form a continuous surface, and the the belly is modified sternum. The turtle’s backbone is fused to the interior of the shell, so unlike a hermit crab that can trade in its shell if it finds something it likes better, a turtle is very much connected to its shell for life. If you find an old shell, its owner long since gone, it’s interesting to examine the bone structure.
Look at those claws! Turtles have remarkably long, strong claws that are used for a number of purposes. Defense, certainly, if needed, but a turtle’s primary defense is its shell. The claws are more useful in helping to grip the ground to power forward when walking on land – a cumbersome endeavour – as well as in digging out the nest site. However, males have substantially longer claws than females. Wikipedia suggests he uses them in foreplay to “tickle the cheeks of the female rapidly up-and-down in a vibratory manner”. I don’t know if this is true or not, but… whatever gets you going.
From underneath you can really see the colours that give the Painted Turtle its name. There are four subspecies of Painted Turtle, all varying in the alignment of their shell scutes and the patterns on their faces. We have the Midland Painted Turtle (C. p. marginata) here. The Western Painted Turtle (C. p. bellii) is also found in Ontario, but only in the northwest, near the Manitoba border.
Turtles hibernate over the winter, burying themselves in up to 3 ft (90 cm) of mud under relatively shallow water. In this environment they are starved for oxygen, but have evolved the ability to survive for up to five months without oxygen at temperatures just above freezing. This is the longest known period of oxygen deprivation of any air-breathing vertebrate. Unsurprisingly, over the winter their metabolism slows to a near crawl, but unlike the Wood Frog, they don’t “die”.
One can often see Painted Turtles in the summer hauled out of the water on a submerged log or rock. They do this to sunbathe, to raise their body temperature since, as reptiles, they are unable to thermoregulate themselves. Their body temperature needs to be at least 65 F (18 C) in order for them to digest their food properly. Interestingly, Painted Turtles, as well as other semi-aquatic turtle species, will only eat underwater.
Raven remained freaked out by the turtle even when I showed her it was harmless. Probably a good thing for any future turtles she may encounter, anyway. I picked the turtle up and took it down to the lake to release it, where it would be away from Raven (both for its sake and Raven’s). I set it gently in the water at the edge, where it remained momentarily, before abruptly extending its limbs and motoring away into the lake. For all their awkwardness on land, turtles are really at home in the water, moving swiftly and with ease. In the blink of an eye, it was gone, hopefully off to find itself a better nesting site than our driveway.