By LESLIE BISHOP, guest columnist
April showers bring more than May flowers: the warmer temperatures and rain are signals to the Eastern Box Turtle to move in search of food and mates.
On a recent trip to southern Illinois, my husband drove on I-69 and saw numerous road-killed turtles and snakes.
The patterns of animals as they move out of their winter hibernation are built into their DNA. These reptiles have distinct territory sizes, habitat requirements for mating and reproduction and movement patterns for finding food.
These patterns mean that they are unable to adapt to human-altered habitats — such as a new major highway — and high mortality is the result. We place these obstacles in their paths, and we can become aware of ways to help them.
While traveling State Road 45, I see my first box turtle for the season in Brown County. I glance in my mirror to be sure no one is behind me and pull off the pavement as soon as it is safe. I jump out of my car, run back to the turtle and place him on the other side of the road — in the direction he was headed — and jump back in my car.
Box turtles have a territory the size of about two football fields. They eat a range of food: snails, worms, insects, spiders, fruits, berries, leaves and many types of mushrooms. They are even able to eat mushrooms that are toxic to other animals, including humans.
Their search for food takes them across roads. If they are removed from their territory, they will attempt to return and probably will have to cross more roads to get there.
A box turtle reaches adult size at age 20 and can live between 30 and 40 years. Thus, each turtle I stop to move likely has a long history. In some cases, the turtle has been around longer than the highways it is crossing.
Box turtles are moving across the roads not only to find food but also to find mates. Females reach sexual maturity at about 7 to 10 years of age. Mating may take place at any time between April and September. However, females have the amazing ability to store sperm and lay fertile eggs up to four years after mating.
After mating, a female seeks out soft soil in a warm, sunny site for nesting. She may travel a mile and cross several roads in doing so. If she perceives that the best place to lay eggs is across the road, she will try to go there no matter how many cars are whizzing by.
If and when she finds an appropriate place to nest, she will lay three to six leathery eggs in a hole about 4 inches deep. She tends to lay eggs in close proximity to the previous year’s nest.
The eggs take two to three months to hatch, but during that time the nest is highly vulnerable to predators. Dogs, coyotes and raccoons dig for the eggs. The hatchlings that do emerge are often prey to the same predators, plus crows, bullfrogs and snakes such as copperheads.
It is thus an amazing feat for a turtle to reach adulthood and avoid all the possible predators at different life stages. This type of life cycle means that turtle populations are especially vulnerable to decline. With long lives, delayed reproduction and high mortality of offspring, the removal of a relatively few adults can have a dramatic effect on population numbers.
Eastern box turtle populations are, in fact, declining, due to several causes: habitat loss, road mortality and collection by humans. Because Brown County and other parts of southern Indiana are blessed by vast forest cover, the box turtle population is healthier here than anywhere in the state.
Yet, the current state of logging on public land is creating a more fragmented forest habitat. To box turtles, habitat fragmentation means disruption of movement patterns critical to survival, reduced territory sizes and increased mortality due to interaction with humans and their machinery.
The International Union for Conservation of Nature has assessed the box turtle as “vulnerable,” which means “high risk of endangerment in the wild.” The box turtle has been listed as “species of concern” in the state of Ohio and as a species of “special concern” in Indiana and Michigan.
We have good reason to be alarmed about high rates of logging on public lands.
Indiana protects box turtles by law, and it is illegal to collect them from the wild. Keeping a box turtle as a pet is not only illegal, but it also prevents vital reproduction in the wild.
How can you help box turtles? Join us in helping turtles cross the roads and educating others about the value of maintaining contiguous forestland for these vulnerable Brown County residents.
Leslie Bishop is a Brown County resident and retired biology professor from Earlham College. She is a volunteer interpretive naturalist at Brown County State Park. She can be reached through the newspaper at [email protected].
