Wood Turtle

Glyptemys insculpta

Cool Fact: * The temperature of the developing eggs determines whether the offspring will be male or female. If eggs incubate above 87.8 °F the babies will be female; if below 81.86°F, they will be male.  

Wood turtles have likely been in New England for about 10,000 years, following the retreat of the last glaciers. Roughly 30% of their total population is in Canada, but their US range is as far west as Michigan and south to Virginia. Studies reveal that densities vary widely, from 6 to 90 turtles per 2.5 acres, with colonies often having more females than males. 

According to the Maine Department of Inland Fisheries & Wildlife, the wood turtle is one of Maine’s rarest turtles and is listed as a species of “Special Concern.” It is found statewide, but wild populations are decreasing. On a positive note, it’s a long-lived species: up to 40 years in the wild. 

Described as a medium-sized turtle averaging 5-8 inches in length, a fully grown wood turtle weighs about 2.2 lbs. It has a well-sculpted brown to gray top shell (carapace) that resembles carved wood, with a central ridge or “keel” made up of a pyramidal pattern of ridges and grooves. The underside or bottom shell (plastron) is yellowish with large dark blotches and orange/yellow coloration on its neck, chin, and legs. Although sometimes speckled with yellowish spots, the head is often dark gray to solid black.   

Wood turtles prefer slow-moving streams or rivers with a sandy bottom and vegetated banks, but will spend the spring and summer months in fields, wet meadows, bogs, beaver ponds, and open forest. The soft muddy areas of the waterways are ideal for overwintering, while sandbars and open canopy areas are prime nesting sites. They feed on land as well as in the water; their diet consists of insects, fish, crayfish, earthworms, algae, grass, leaves, berries, tadpoles, and even baby mice.   

Wood turtles don’t reach sexual maturity until they are 12-18 years old. They are oviparous, meaning they produce offspring by laying eggs and do not provide parental care. The courtship ritual consists of several hours of “dancing,” initiated by the male, who nudges the female’s shell, head, tail, and legs. They approach and back away from each other, raising and extending their heads, then lower their heads and swing them back and forth.  

Mating typically occurs late August through November, with breeding taking place in the water. Females are particular about nest location; they prefer elevated areas to avoid flooding and predation and are particular about soil temperature. Egg laying (they lay 3 to 20 eggs) occurs from May to July; the female covers them with dirt and leaves them to incubate hidden from predators. After about 8-10 weeks, the hatchlings dig their way to the surface, ranging in size from 1-1.5 inches in length. At this stage, they are very vulnerable and often fall prey to skunks, raccoons, foxes, otters, bullfrogs, birds, and other carnivores; survival rate to adulthood is low. 

Human activities are the main cause of the turtles’ decline. Habitat destruction (both land and water), road traffic, encounters with forestry and agricultural equipment, invasive plants in nesting areas, poor water quality, disease, and illegal collection for the international black-market pet trade have cumulative negative impacts. Due to significant population declines over the last century, wood turtles have been petitioned for listing under the Endangered Species Act.  

 Some more “cool facts” about wood turtles:

• The wood turtle has homing capabilities. After an experiment involving them finding food in a maze, results proved they have locating abilities similar to that of rats.
• Wood turtles stomp their front feet for earthworms, with footfalls presumably mimicking rainfall that brings worms to the surface, where they are then eaten. This behavior also imitates vibrations caused by moles, sometimes causing worms to rise to the surface.
• Female wood turtles often use the same nesting site for years. They mate with multiple males and can store their sperm for several years before laying fertilized eggs.
• Basking in the sun serves many purposes: maintains body temperature, helps promote muscle activity and digestion, encourages leeches and other parasites to drop off, and triggers production of vitamin D, which is essential for strong shells.
• Turtles have no teeth – their jaws are hard and bony with sharp edges for tearing. 

 Written by Jayne Winters – March 14, 2025 

 Resources:

• https://www.maine.gov/ifw/fish-wildlife/wildlife/species-information/reptiles-amphibians/wood-turtle.html 
• https://www.thefactsite.com/tag/reptiles/ 
• https://www.wildlife.nh.gov/wildlife-and-habitat/species-occurring-nh/wood-turtle 
• https://www.massaudubon.org/nature-wildlife/reptiles-amphibians/turtles 
• https://en.wikipedia.org/wiki/Wood_turtle