Where do the Turtles go in the Winter?
The turtle pond, at 5,000 feet elevation, covered with a sheet of ice. Photo by Michael Parker, Interim Chair of Biology at SOU.
Michael Parker demonstrating how to measure a Western Pond Turtle’s age. Michael Parker has recorded over 80 Western Pond Turtles in the turtle pond at Willow-Witt Ranch.
The western pond turtle (the only native turtle in our region) is widely distributed along the west coast of North America, primarily west of the crest of the Cascades and Sierra-Nevada mountain ranges. In Oregon, western pond turtles most commonly occur below about 3,000 feet elevation and inhabit a variety of habitats from streams and rivers to wetland ponds, lakes, and reservoirs. What makes the turtle population at Willow-Witt particularly interesting is that it represents one of the highest elevation breeding populations of this species in the region. Since 2015 we have been studying this population to gain insights that may help us understand how turtles will adapt to a warming climate. To date, we have captured, weighed, measured, and given individual identifying marks (and names!) to almost all the turtles in the pond. Most folks are surprised to learn that over 100 turtles call the pond home.
Western Pond Turtles basking in the sun. As cold-blooded reptiles, turtles bask to regulate their body temperature and to absorb UVB in order to stay healthy.
Most Willow-Witt visitors encounter the resident pond turtles during the spring and summer when they are highly visible basking in the sun. But what about this time of year? What do the turtles do and where do they go during winter? In many lower elevation populations, particularly those inhabiting streams and rivers, turtles leave the aquatic environment to over-winter on dry land. They do not dig burrows, or bury themselves, they simply settle down onto the surface of the ground, pull in their head and legs, and wait for spring. But what do they do at 4,800 feet when the ground is covered with snow for several weeks? We answered that question last winter by following a group of 6 turtles (3 female; 3 male) on whose carapace (upper shell) we had attached radio transmitters. What we discovered is that the turtles spend the entire winter in the pond. A vision of turtles buried in the mud, unmoving for weeks, is probably what is going through most reader’s minds at this point. But what we observed is that, although less active than during the warmer months, the turtles actually moved around quite a bit within the pond throughout the winter, even when the pond is partially frozen. We also found that as early as mid-February, when days are getting noticeably longer, turtles may emerge to bask for short periods. By March, on most sunny spring afternoons turtles can once again be observed moving about, warming themselves in the sun.