Turtles in Winter: Bundle Up!
Ontario’s turtles, so fond of sunbathing in summer, are also well-equipped to survive our freezing winters.
When the temperature drops, says Hope Freeman, a Master’s student with the McMaster Ecohydrology Lab studying the winter habits of these shy shelled reptiles , our region’s six species of native turtles take refuge in the unfrozen water and organic matter in different water bodies such as wetlands, ponds, lakes.
How can they survive an entire Ontario winter?
First of all, turtles can survive months without coming to the surface to breathe. They can breathe the oxygen dissolved in the frosty winter waters. And here’s a fun fact that Hope enjoys sharing: turtles can breathe through their bums. When ice covers the water body and they cannot come to the surface for air, turtles breathe through special glands in their cloaca (scientific term for a turtle’s bum) as well as special glands in their mouths.
Second of all, freshwater turtles are ectothermic, or cold blooded, meaning their body temperature is dependent on their environment, so in the winter they often get quite cold. They can stay alive for months in near zero temperature waters, going into a “sleepy” state, slowly using up all the energy and other resources they collected in the summer months.
Hope described a term known as the “freshwater turtle resilience zone”, where the ideal refuge for a turtle’s long winter rest is in waters with stable, cool water temperatures, around 0°C, dissolved oxygen they need to breathe, and, at least 50 cm of water, which can act as a buffer against the thickening ice or as insurance against being exposed to freezing air in case the water level drops over the winter.
It’s not a classic, hibernation-type sleep. “Their metabolism slows down, but they still have some awareness of their environment, freshwater turtles have been observed coming up to the surface and grabbing a breath of air at the water surface in ice melt patches,” explains Hope, “they may also bury into the sediment if an otter or other predator succeeds in breaking through the ice on the hunt for food.”
There are a few things you can do to give shelled friends a helping hand:
1) Assist them across the road in the direction they are going,
2) If you find an injured turtle call the Ontario Turtle Conservation Centre, and
3) If you absolutely have to alter a beaver dam, do it in late spring or early summer rather than in fall or winter, when a sudden drop in water level could leave multiple turtles high, dry and frozen, resulting in their death.
Thanks to Hope Freeman, who provided this information at the Parry Sound Nature Club’s March 16 presentation. Go to the Parry Sound Nature Club Facebook page for Freeman’s full presentation.
Helen Kohl is a member of the Parry Sound Nature Club.