TURTLES SWIM UNDER ICE

by Whit Gibbons

February 12, 2006

Whether you believe global climate change is real or not, my winter so far has been warmer than usual. A cold winter makes spring a more rejuvenating experience. This was especially true at the end of a memorable winter many years ago in Michigan as I stared into icy waters looking for life. Any kind of life.

Wanting to work with reptiles, I found Michigan winters excessively long. Being a herpetologist is not a prerequisite for having this attitude, but someone interested in reptiles is unlikely to find much of interest amid ice and snow. By early April of that year, the winter had gone on long enough to suit me. I wanted to see a lake without ice. Nevertheless, when someone phoned to say that a turtle had been seen swimming beneath the ice in open water around a boat dock, I ventured out to the icy lake.

All herpetologists "knew" that turtles were not active in cold weather. Therefore, we wasted no time looking for turtles in half-frozen lakes. But the day was sunny, in fact brilliant, and by my Alabama standards the winter had overstayed its welcome by several weeks. I was anxious to see my first reptile of the year; even a single, disoriented painted turtle would be a welcome sight.

Icy cold, clear water surrounded the wooden dock. The open water stopped at the edge of the ice shelf that covered the remainder of the lake. I was disappointed. The lake was not really accessible; only a few hundred square feet around the dock had thawed. But the sky and the water were clear, so I decided to take a look. Standing in the bow of a cold aluminum boat, I pushed out into the water and used one oar as a pole to push along the shoreline. Seconds later I saw a painted turtle swimming along the bottom of the lake. I used my dip net, turning my first reptile sighting of the year into my first capture: a male painted turtle, its black shell margined with crimson, its black head and legs adorned with bright yellow stripes. A handsome creature, and amazingly active for a reptile in ice water. I assumed this was an aberrant animal as anxious to rush the season as I was.

While I was putting the turtle into a collecting bag, the boat was assisted by a cold draft of late winter wind and drifted across the open water toward the ice shelf. I peered into the crystal clear, pristine waters. The ice at the shelf’s edge was like a glass counter. I stared and marveled. Turtles. Dozens of painted turtles. Crawling. Moving. Swimming along the bottom beneath the transparent ice shelf. The scene brought a rush of emotional warmth in stark contrast to the physical world of frigid water, freezing air, and ice-encrusted lake.

My interpretation of the phenomenon I had stumbled on was not particularly profound. I concluded that the turtles were trying to raise their body temperature on what was probably their first view of the sun in months. One reason for trying to get warm enough to be active when the lake is still ice-covered may be related to their breeding season. Whatever the case, the painted turtles had taken advantage of the opportunity to raise their body temperature and were active under near-freezing conditions.

Along with my amazement, and the unneeded reminder that Michigan is cold much of the time, came the realization that I had witnessed a heretofore unknown phenomenon. The observation inspired me to write my first technical publication in a scientific journal. I viewed publishing as a sacred ritual, and seeing the paper appear in a reputable scientific journal gave me a confidence I had lacked. I could actually observe a herpetological phenomenon and write about it for other people to read. The event also confirmed for me that reptiles are remarkable and mysterious. But perhaps the most important lesson was one that has continued to be part of my learning experiences. That is, animals do not always do what our preconceived notions prepare us for, and they can offer us biological mysteries we did not even know existed.

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