What Do Painted Turtles Do in Winter?

Painted turtles in climates like ours hunker down for winter and don’t emerge until the sun is out and plants are sprouting again in the spring. On particularly cold, blustery winter days, I tend to think that isn’t a bad plan!

Painted turtles bask at Nature Boardwalk in this photo from April 2011.

Unlike humans, which need to keep a fairly consistent body temperature regardless of their surroundings, painted turtles are ectotherms, which means their body temperature depends on their environment. In the winter, as the pond begins to freeze, the painted turtles at Nature Boardwalk at Lincoln Park Zoo find a nice spot in the mud at the bottom, fairly close to shore and under the ice, where they will remain (more or less) for the rest of the winter. Their body temperature drops to approximately that of the surrounding water. Their metabolism slows to a crawl, and they won’t come up for air until spring.

Even though they abstain from breathing, they still have some minimal oxygen requirements, which they meet by taking up oxygen from the surrounding water through their skin. It’s therefore important that the dissolved oxygen content in the pond’s water is adequate all winter so the turtles can take in oxygen. At Nature Boardwalk, aerators run all winter to keep patches of the pond from freezing over completely. This ensures that dissolved oxygen levels are sufficiently high. Taking up dissolved oxygen in water through the skin is obviously not as effective as breathing, but the turtles seem to make it work!

Last year the turtles we were tracking all overwintered in the vicinity of the island. This year it looks like a similar pattern is occurring even though we’re tracking different turtles this time. The turtles are slowing down, but still moving around a bit, as they settle in. This is a map of three of the turtles’ locations on December 14, 2011.

Perhaps the most interesting thing about all this is that even with their metabolisms practically shut down—their body temperatures nearly freezing—the turtles do in fact move around. Last year we tracked them through the winter using radio telemetry. While the turtles stuck to the edges around the island in the pond, they did mosey their way around, often making small, but perceptible, movements from week to week.

Urban Wildlife Institute Intern Mason Fidino uses radio telemetry equipment to pinpoint the turtles' locations in the pond as they ready themselves for winter.

We wouldn’t know this without radio telemetry. In fact, radio telemetry has helped scientists make many discoveries about the physiology of how turtles overwinter; without this technology we’d know a lot less about these amazing adaptations. We don’t expect to see the painted turtles at Nature Boardwalk for several months now, but we’ll still be ‘keeping an eye’ on them via their radio transmitters!

Vicky Hunt

P.S. Learn more about what zoo reptiles do during winter with Curator Diane Mulkerin’s blog!

Comments

What an excellent way to engage people with science, getting them interested, as well as finding out more about as fascinating a species as the painted turtle! Thanks :)

We found a painted turtle in our driveway a few days ago on a exceptionally warm day for December in Canada. It is strange as we do not have any ponds around here as we live in the city but it was covered in mud, and as we knew it was going to get cold that night we brought the turtle in the house. We are now wondering if we would be ok to release it into a local pond where we know there are other turtles or would we be better off keeping it inside until the weather warms up in the spring?

We would appreciate your opinion on this matter. Thank you and we look forward to hearing from you soon.

Gillian.

Ps. He seems to be healthy ;)

Thanks for the note, Gillian. We passed the question on to Reintroduction Biologist Allison Sacerdote, Ph.D., and she gave us the following advice to pass along:

"This is a difficult question because we don’t know the area or where the turtle came from. If they have small ponds nearby (< 3 km), they could take it to the closest one and release near the shoreline and let it find its own way. However, if the nearest pond is on protected land, there may be regulations against releasing animals there, so I would not suggest they do that. They may want to contact the landowner if there is park land nearby and have the biologists make a decision on releasing the turtle there. Alternatively, there may be other wildlife resource centers near them that they could contact. They should not keep it over the winter. The turtle could develop health issues in captivity that could be transmitted to a wild population upon release in the spring."

HI Thanks for your website it really helped with a school project.

We brought home a baby painted turtle a year ago, as where he was swimming was a hug lake and lots of catfish around and we had a pond in our backyard. She loved it back there with our fish and frogs and never left, we took her in the house and kept her in a aquarium overwinter with a heat light and a day light for her to bask in on her rock. She has done very well and has now tripled in size, she's around four inches wide now. I was wondering if she will live out in the pond during the winter as we plan on leaving the fish out there next fall. It is about five feet deep now and will put in an aerator also. We live in Wisconsin. She seems very healthy but eats Turtle food in a can and doesn't seem to eat any live bugs, I had thought of putting her in a pond nearby, but I'm not sure if she would survive now since she is domesticated.

My husband brought home 2 turtles a few weeks ago and is now building a pond in the back yard for them. The little one was hissing for a few days but now seems to like his new home.
I can't tell if they are eating the apples, lettuce or zuchinni he puts out for them. They love it when he rubs the underside of their necks. They stick thier heads out as far as they can.

I'm surprised by these people

I'm surprised by these people who are picking up wild animals and taking them as pets (even backyard pets). Seems very irresponsible...

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