Before winter sets in, all reptiles and amphibians must retreat to a location that provides shelter against the temperatures that would be lethal to their cold-blooded system. While some find refuge underground, others rely on the protection afforded by water and seek out a place on the bottom of an aquatic setting in which ice is unlikely to develop, even during periods of intense cold.
All turtles that live in the Adirondacks belong to this second group, including the wood turtle, a seldom encountered species that exists in limited numbers in scattered locations, especially in the eastern half of the Park.
The wood turtle is comparable in size to the painted turtle, yet the wood turtle can be recognized, in part, by its gray-brown top shell, known as a carapace, that exhibits a slightly raised line, or keel down the middle. Also, younger wood turtles, those less than 20 years old, have noticeably elevated, or ridged centers to the major scales that compose their carapace. This creates a unique cross-furrowed or bumpy appearance to their back. Adults that are well into their 30’s and 40’s lose much of this sculpted feature, however the carapace of these individuals rarely has the same smooth texture of the painted turtle’s carapace. Additionally, the upper portion of their neck and legs exhibits a bright yellowish-orange color.
Unlike the painted and snapping turtles, the wood turtle does not prefer to reside in the quiet waters of ponds, marshes, and the weedy shores of lakes. Rather, this reptile is more attracted to large, sluggish brooks, alder-choked streams and meandering rivers, especially those that flow through wooded areas. Because the wood turtle is not as well adapted for absorbing oxygen from water as other turtles, it must seek out those aquatic settings in which there is a high concentration of this dissolved gas. Sections of water in which a series of small, swirling cataracts and periodic waterfalls allow the air to mix with water forming a solution rich in oxygen are ideal. Even the waterfalls on the spillway on a beaver dam can create favorable conditions downstream for the wood turtle.
As cool weather becomes more the rule in October, the wood turtle returns to a favored section of waterway to find an overwintering site. Turtle researchers have determined that the wood turtle has the ability to remember the locations of good food sources within a fair distance of the water and where favorable underwater shelters exist. Sandy or muddy bottom sections of a riverbed are highly preferred, as the wood turtle partially buries itself in the bottom sediment in order to avoid being easily detected by the occasional otter or mink that prowls these waterways for a meaty meal. Also, areas that contain scattered chunks of debris, such as a submerged log or sunken boulder, which create eddy currents and greatly reduce the force of the oncoming water, are ideal as overwintering sites.
In New York, the wood turtle is listed as a species of special concern. This is partly due to the loss of wooded habitat, and development issues near rivers and streams used by the wood turtle. In summer, the wood turtle regularly exits the water during the day to search for food along the shore. It may also venture up to a quarter mile inland to consume edibles. This is why disturbances of areas close to flowing water can adversely impact the success of the wood turtle.
The increase in the number of medium size woodland predators, like the fox, raccoon, and fisher over the past few decades is also believed to be impacting the population of wood turtles. Not only do these opportunistic meat-eaters attempt to break open the protective shell of an adult and eat the tasty contents inside, but they are also masters at locating the eggs laid by females. The wood turtle produces fewer eggs than most reptiles, as an adult only bears from 6 to 12 eggs each season. Even though the wood turtle can live for over 40 years, it takes at least 15 years for a female to reach sexual maturity.
Climate change is another factor impacting the success of the wood turtle. Unusually heavy periods of rain and thaws during the winter can create extremely strong currents in rivers and streams, which can disturb the riverbed and uproot a hibernating wood turtle from the sediment in which it has become embedded.
The wood turtle is a unique reptile that may occasionally be seen by an observant hiker, camper or fisherman during summer in some back-woods location near a meandering brook or river. For the next 4 months, however, this distinct reptile is buried in the sediment in a dormant state, and its success at surviving this season is based on a lack of any serious flooding.
Photo of Wood Turtle, courtesy the United States Geological Survey.
A version of this article first appeared on the Adirondack Almanack in December, 2012.