SOME ECOLOGICAL ASSESSMENTS ONLY REQUIRE A SAMPLE SIZE OF ONE
by Whit Gibbons
June 17, 2012
During my career as an ecologist I have acquired quite a bit of knowledge about turtle biology, sometimes in a classroom setting, more often in the field. Field experiences tend to leave a lasting impression, and the following one left an indelible mark.
As my son and I slogged through deep mud removing turtle traps from the Potomac River before the water began to rise in the freshwater tidal zone, two colleagues of mine stood on the bank watching us. (In their defense, we were taking them to the airport and had stopped to check traps on the way.) We all had a vague assumption bordering on knowledge that a submerged snapper will try to escape whereas one out of the water will bite you if it can.
As Mike and I trudged toward a trap, my shin thudded against a large object. Northern red-bellied cooter, I thought, eager to catch my first specimen of this beautiful turtle. I leaned over with my face grazing the water's surface and reached down through a foot of water into the knee-deep sludge, feeling around for the mired-in-the-mud turtle. What an easy capture this would be.
I moved my hands to orient them on the sides of the shell, and felt something clamp my left ring finger. Uh oh. I tried to yank my hand back. It did not budge. When I relaxed my hand and finger, I felt the mouth of a big turtle begin to gradually open. I yanked again expecting to pull my finger free. The mouth grip tightened. The turtle stayed solidly stuck in the mud and my finger stayed solidly stuck in the turtle's mouth. On the shore, Justin and Steve began to laugh. My son said, "Dad, I think the water's rising." The tidal amplitude was over a foot, more than enough to put my head under water.
My arm was stretched out as far as possible and my hand was gripped firmly in the turtle's mouth. Each time I started to pull the animal upward, it clamped down with renewed ferocity, which stopped my progress. Watching the rising tide, Steve and Justin realized the situation was not actually funny. They also realized that I had the car keys in my pocket. Getting me out of the Potomac River before I drowned--and in time for them to make their flight--generated a community sense of urgency. We conferred in earnest. Steve and Justin couldn't wade in and help rescue me without spoiling their good clothes, so we decided I would just have to endure the bite and manhandle the turtle up through the mud. I pulled while Michael dove under the water and pushed the turtle upward. He did not have to worry about being bitten as the turtle clamped down harder than ever on my finger. Justin and Steve watched anxiously from the shore.
Once the turtle reached the water column above the mud, I moved it rapidly above the surface. When it broke the water's surface, to my surprise and overwhelming delight, it opened its mouth. Out came my finger. With my other hand I grabbed the snapping turtle by the tail as it tried to escape. Mike and I hauled it to shore, weighed it (22 pounds), marked its shell with a portable drill, and released it back into the river. We had all acquired a little knowledge about turtle behavior. We had also learned what a finger looks like when it has been cut so you can see the bone from either side. Steve and Justin made their flight, the finger healed, and the turtle is presumably swimming around in the Potomac waiting to be recaptured.
We flipped snapping turtle conventional wisdom on its head that day. A snapper will bite when under water and let go when out of water. Some scientific inquiries only require a sample size of one. But you are welcome to make your own experiment if you want.
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