Eastern Painted Turtles: Where Do They Go in Winter?
—Henry Myers, Environmental Educator
Photo credit: Fairfax County Schools
The eastern painted turtle is one of my favorite animals found at the Rye Nature Center. During the summer it is common to see these turtles sunning themselves on logs in Nanderwhere pond. From the edge of the pond their shells look dark and drab, but when they're in the hand that changes; underneath their carapace (upper shell) are bright yellow and red colors.
During the winter months these turtles have an amazing way of dealing with the cold. The adult turtles head to the bottom of the pond and enter a dormant state. They will stay under the water or ice for 4 to 5 months. Once the turtles are under water their body temperature drops to around 39 degrees Fahrenheit. This low body temperature allows the turtle to burn one tenth of the energy it normally would.
While under water the painted turtle is able to exchange some oxygen and carbon dioxide across membrane linings in its throat and under its tail. But, during the late winter (especially if the pond is frozen over) the oxygen level will drop to zero. When this happens the turtle breaks down glycogen (a sugar) that is stored around the turtle's organs. This is a good energy source without using oxygen. However, there is a drawback, when glycogen is broken down it produces lactic acid which is toxic at high levels. To counteract the lactic acid build up minerals are released from the turtles shell and bones.
Even more impressive (in my opinion) is how newly-hatched painted turtles survive the winter. The mother turtle digs a hole (usually 2-4 inches deep) and lays about 10 eggs in the spring. The eggs hatch in the fall and the hatchlings stay underground in the nest all winter long. Because the nest is only 2-4 inches below ground it is above the frost line. So these young turtles freeze solid, relying on a type of antifreeze their bodies produce to protect their main organs from the cold. In the spring the turtles thaw out and, finally, make their way to the pond. Below is a link to a video of this amazing feat.
So next time you're hiking around Nanderwhere pond in the winter think about those amazing painted turtles under the ice and underfoot.
Video Link to Frozen Turtles:
http://www.bbc.co.uk/programmes/p0060vdd
