by Carl Strang
My first job after graduate school was an assistant professorship at Dickinson College, a small liberal arts school in south central Pennsylvania. One of my responsibilities was to manage The Reineman Wildlife Sanctuary, a large privately owned piece of forested Appalachian mountain ridge. Herps were abundant there, and for research subjects I could have gone with either salamanders or turtles. Turtles had been a childhood love, and so I decided to see how two terrestrial species, the eastern box turtle and the wood turtle, were managing to coexist in that forest. Eastern box turtles were common in northern Indiana, so I was acquainted with them.
Wood turtles were new to me.
Most of the area was a forest growing on rocky soil.
Lower areas were relatively level, but much of the property was sloping mountainside. The lowlands also were divided by streams that were intermittent to varying degrees but always had some pools. I caught as many turtles of both species as I could find, and notched the edges of their shells in patterns that allowed me to recognize individuals. I followed selected turtles in a decidedly low-tech way.
The waterproof adhesive tape only held on for a short time, so the turtles were not carrying these backpacks into hibernation. I never found a sign that this device impeded or endangered them in any way. I was able to map and measure the turtles’ travels by taking up the thread. I also sat and observed them from a distance.
My principal findings can be fairly quickly summarized. Box turtles are thoroughly terrestrial, and they occurred throughout the Sanctuary, from the lowlands to the highest parts of the mountain ridge. They seldom contacted standing water, and this limited their activity. They had small home ranges. Much of the time they stayed buried in the leaf litter, coming out most predictably during rainy periods. They were visual hunters, and ate animal foods almost exclusively. When they did come out on dry days they did a lot of sitting and waiting for prey to move, and didn’t travel very far. The only times they covered a lot of ground were on rainy days.
Wood turtles were consistently active, and traveled far on dry as well as rainy days. They had much larger home ranges than box turtles. They ate both animal and plant foods, their most notable departure from the box turtle diet being their frequent consumption of green leaves. This added activity exposed them to desiccation, but they frequently entered streams during their wanderings, and sometimes remained in the water for days at a time. Since standing water was limited to the lowlands, wood turtles were limited to that relatively small portion of the forest.
The turtles revealed a clear tradeoff. Box turtles were widely distributed in space, but limited in the times when they could be active. Wood turtles were active all the time, but this tied them to the limited areas where they could reach open water. This significant impact of physical factors (water, humidity, temperature) was an important departure from the birds and mammals with which I had been most familiar, and a lesson I carry whenever I consider the reptiles and amphibians of northeast Illinois.