Trapped Beneath the Ice?
In temperate climates, many amphibians and reptiles hibernate (brumate) during the cold winter months. Here in Minnesota, my current state of residence, it gets cold (mean winter temperate = 14° F / -10° C, record low = - 60° F / -51° C; MNDNR 2015) - brrr. Yet, Minnesota is home to 11 species of turtle (one of which is the invasive Red-eared Slider). This leaves turtles with roughly 5 - 7 months of good weather to breed, lay eggs, and feed to build up fat reserves.
So what do Minnesota's turtle do in the winter time..?
To avoid these subfreezing temperatures, Minnesota's turtles seek refuge under the ice in ponds, lakes, and rivers that do not freeze solid. Hatchling Painted Turtles (Chrysemys picta) are the exception, as they typically overwinter in the nest cavity and emerge the following spring (Paukstis et al., 1989; Gibbons and Nelson, 1978; Hartweg, 1944). There is also evidence that Blanding's Turtles (Emydoidea blandingii) may also occasionally overwinter in the nest cavity, surrounding uplands, or at the wetland edge (Dinkelacker et al., 2004; Linck and Gillette, 2009; Standing et al., 1997).
Under the ice turtles slow their metabolisms, and either diffuse all required oxygen through their skin and other mucus membranes (Belkin, 1968; Gage and Gage, 1886; Ultsch, 1989), or simply hold their breath if in an anoxic (without oxygen) environment (Jackson 2002).
Though much less mobile under the ice during the winter months, turtles do move around some! Below are two short videos taken on December 24, 2015 near St. Peter, Minnesota. Both turtles were observed in a recently frozen pond. Air temperature was 28° F (-2° C). Ice was approximately 1 - 2 in (2.5 - 5 cm) thick. Turtles are tough!
Citations not linked to in text:
Linck, Madeleine and Laurence N. Gillette. 2009. Post-Natal Movements and Overwintering Sites of Hatchling Blanding's Turtles, Emydoidea blandingii, in East-Central Minnesota. Herpetological Review 40: 411-414.
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