Wednesday, January 6, 2016

Nativer Species Profile - Wood Turtle

Because I am writing this in January, I would have a very difficult time locating one of my favorite animals - the Wood Turtle (Glyptemys insculpta).  If I were to find one now, it would be somewhere underwater either buried in the mud or wedged under a rock or log.  There it hibernates motionless for several months, living on stored resources and absorbing oxygen from the water.  It probably disappeared under the water sometime in October and won't appear again until late April or May.

Wood Turtle (June 2008)


The Wood Turtle is one of ten species of turtle that can be found in Michigan.  Six of the species are considered to have stable populations (Map Turtle, Musk Turtle, Painted Turtle, Spiny Softshell Turtle, Red-ear Slider, and Snapping Turtle), one is Threatened (Spotted Turtle), and three are listed as Special Concern.  The Wood Turtle falls in this last category along with the Eastern Box Turtle and Blanding's Turtle.  This status means that the Wood Turtle has no legal protections under the Michigan Endangered Species Act.  Fortunately it is protected under a Michigan Department of Natural Resources Director's Order that prohibits killing, taking, possessing, selling or buying them from the wild.

The Wood Turtle is a fairly small turtle, growing from 5 to 10 inches long as an adult.  Their upper shell (carapace) is tan to dark brown in color, with well defined scutes (plates).  The scutes have a series of growth rings, much like a tree - contributing to its name.  In younger turtles, the growth rings can be used to determine age, but the rings are often worn away in older individuals.  Their lower shell (plastron) is usually a dark yellow with brown patches.  This color scheme is also found on the exposed skin of its head, legs, and tail - the upper surfaces are brown (with yellow or orange spots) and the lower surfaces are yellow or orange.

Wood Turtle - note the "sculptured" shell, dark upper surfaces, and yellow underparts

The Wood Turtle is partially named for its habitat preferences.  It is typically found in the floodplain forests of clear running streams and rivers with sand or gravel bottoms.  Unlike most aquatic turtles, the Wood Turtle is commonly away from water during the summer months.  They often disperse as much as 1/3 mile into forests to feed on the leaves of herbaceous and woody plants, berries, mushrooms, worms and other invertebrates.  When in the water it feeds on aquatic plants, invertebrates, and rarely on dead animals. 

Wood Turtles commonly feed away from water during the summer months
 
Another habitat requirement is sandy soil for nesting.  Nesting typically takes place in June.  Female Wood Turtles excavate a shallow nesting cavity and deposits up to 18 eggs.  Hatchling turtles may emerge in August or September, or they may remain in the nest until the following spring.

A female Wood Turtle laying eggs on a sandbar in Mt. Pleasant
 
In Michigan, Wood Turtles are only found in the northern half of the Lower Peninsula and across the Upper Peninsula.  Overall their range extends from from Minnesota and northern Iowa in the west to the Atlantic coastline from New Brunswick and Quebec in the north to Virginia in the south.  Isabella County is near the southern edge of their range in Michigan.  There seems to be healthy population of adults in the county, but I have rarely encountered a young Wood Turtle in the wild.

Basic Information

Wood Turtle 
Glyptemys insculpta

Size:  5-10” long

Habitat:  rivers and streams with woodland floodplains

Eats:  plants, berries, mushrooms, earthworms, slugs, aquatic invertebrates, carrion (rarely)

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