Riverside Residents

Do you like to sit in the sunshine, slide into the water to cool off, or dig in the sand? You would if you were a turtle! Like humans who enjoy sunbathing (with sunscreen on, of course), turtles like to bask in the sun. Because they are ectothermic, or cold-blooded, they rely on the sun to get their metabolism going. A turtle’s dark shell also absorbs heat, so when sufficiently warmed, it slips into the water to swim, hunt for food, or escape danger. Turtles dig in the sand to make nests.

June is the nesting month for all nine Michigan-native species of turtles. Females climb out of the water onto shorelines that have soft sand or soil. Using their hind feet, they dig holes, lay eggs, arrange them, and then refill the holes. A female never sees her eggs or the young. The sun incubates the eggs for 60 to 90 days, depending on the species, with hatching likely to occur in late August to early September.

You may notice broken pieces of white eggshells scattered over the ground. That is the work of predators, often raccoons and skunks, but also foxes, coyotes, or minks, who use scent clues to find turtle nests. The longer a nest escapes detection, the better the chances of hatchlings appearing.

One turtle you’ll find in Michigan, the spiny softshell turtle, is rather odd-looking. Instead of a hard, bony shell covered with scutes (scales), the spiny softshell’s carapace (top shell) and plastron (bottom shell) are flat, smooth, and flexible like leather. The olive green, or brown, shell is marked with dots and circles if it’s a male and blotches if it’s a female. Small spines can be found at the carapace’s front edge.

The spiny softshell turtle’s long, pointy snout is used like a snorkel to breathe air above the surface while its body is submerged. It can also absorb oxygen underwater through its long throat or through its cloaca (posterior opening).
Inhabiting rivers, lakes, or ponds, spiny softshell turtles can escape danger by swimming fast or concealing themselves in muddy substrates. Their diet includes crayfish, tadpoles, aquatic insects, and various other fish.
When you venture out to rivers, marshes, or ponds, look for turtles and appreciate their unique lifestyles.

Turtle Talk

Swim fast. Map turtles bask on rocks in many of our Great Lakes Bay Region rivers. They are appropriately named for the topographical-like markings on their carapace. Being rather shy, they dive into water or hide under logjams as people approach in a kayak or canoe. They are stronger swimmers than other turtles, so they can inhabit rivers with strong currents.

Eat well. When hungry, female map turtles use their wide jaws to crush shells of snails, clams, or crayfish. Males, on the other hand, prefer aquatic insects.

Dive in. If a female map turtle’s clutch of six to 20 elliptical, flexible-shelled eggs hatches, the hatchlings head directly to water, swimming and diving without any lessons from their parents.

Keep warm. Some hatchlings of map, spiny softshell, and painted turtles may overwinter in late nests, and won’t emerge until the following spring.

Stay safe. Turtles face many threats to their survival. Turtles trying to cross roads are crushed by vehicles. When collected for pets, or becoming prey for other animals, the adult breeding stock is diminished in the wild. Their habitats are degraded by invasive plants such as phragmites. People on motorized watercraft scare turtles off basking sites and nesting areas, and homes and commercial developments reduce the size of natural habitats.