Gone Underground

It's hard to believe that November is upon us. This has been a picturesque autumn, but as of this past weekend, nearly all of the trees in our area are bare. The oaks are holding on to half their inventory, but they always do, it seems, until Thanksgiving or so (or from the weight of the first snow).

I took these pictures in our back yard in the summer of 2008 of a box turtle who lives there. I have not seen him since July, but he has gone and returned before. Even if I knew his exact whereabouts, I would not be seeing him for the next six months.

Box turtles, like all reptiles in "cold country" hibernate for nearly half of their long lives. This turtle is about thirty years old, but he has spent nearly half of that time hibernating from November through early April deep under the sandy soil and fallen leaves. (Approximate age can be determined by counting the growth rings in any one the scales in the picture below. Double-click photos to enlarge.)

When the first signs of frosts appear, the box turtle finds some nearby water to soak in for a couple days (this both hydrates the body and purges the GI tract for the winter). Once the GI tract is purged, the turtle will not eat anything for the next six months. He will find his favorite hibernation den or dig a new one in the soft earth. (They are known to dig down as far as two feet to ensure coming to rest below the frost line.)

After settling in, they close their shell tight, and let their body temperature drop to the temperature around them (as is always true for cold-blooded creatures). Typically, the subterranean temperature during hibernation is in the mid forties, but they can survive lower temperatures provided they do not actually freeze. In this nearly comatose state, the turtle’s vital functions are almost unperceivable. The heartbeat and breathing is virtually nil. The metabolism all but shuts down. (We speak of bears hibernating, but warm-blooded mammals never shut down this completely.)

Not until the temperatures of spring warm the earth around them do they awaken, gradually come back to life, and dig themselves out of the deep den. This rest is an essential part of their life-cycle, breeding, and general health. Adult box turtles kept inside at room temperatures and “not allowed to hibernate usually experience a progressive physical and mental decline.”

The turtle in these pictures is technically called an "Eastern Ornate Box Turtle." He is larger and more orange than any of the dozens of others I've seen in the wild. There is a female nearly his size that is somewhere out there with him. Her coloring is much more muted, and she has almost no orange in her flesh, scales, or shell. I wish I had taken similar pictures of her when I last had the chance. I hope to see her again in the spring as well.

Box turtles have been an interest of mine since the 1980s when I first became familiar with them in my wife’s home state of Kansas, where they are plentiful. I am less interested in fresh-water marine turtles, the painted turtles and sliders I see along creeks and rivers. They spend their winters underwater in the mud--with no access to air. This is remarkable considering they breath air the rest of the year.

While snorkeling in Hawaii last February, I encounter some isolated sea turtles. Much like in a Jacques Cousteau documentary, one of these huge turtles allowed me to hold the sides of his shell as he pulled me along underwater. Sea turtles are powerful swimmers with the thrust to swim from human clasp (and some others did when I tried), but for some reason the one I bumped into first didn’t seem to mind towing me along until I had to let go and come up for air. That was very cool, but I know little about sea turtles. It’s box turtles with their fascinating mechanical shell and slow unthreatening ways that have held my attention through the years.

You may be wondering: How can you tell the difference between male and female box turtles? It's quite easy if you know what to look for (and it’s not what you’re thinking).

First, the eyes of the male are almost always red or deep orange. This is statistically possible of females but not typical. Second, the male turtle’s tail is wider and longer than the female’s (this is because it has a double purpose and houses necessary parts for breeding).

Third, the rear claws of the male are much larger and more aggressively curved than the female’s rear claws. This feature is due to the unique challenges of breeding; the claws serve as grappling hooks on the opposing rim of the female shell. (Without those hooks it would be impossible to hold an amorous embrace, and the species would die off.)

And fourth: perhaps the most amazing part of the turtle design is the fact that the male plastron (the belly of his shell) is concave. It's hard to see it in this picture, but the shell actually goes in on the male and not on the female.

Think of the way a stack of bowls rest inside each other in the cupboard. Now imagine two bowls up-side-down. To a lesser degree, the male plastron (bottom shell) is designed to "nest" to the convex shape of the female carapace (her top shell). It is a subtle detail but without this concave accommodation in shell design, the male’s attempts at wooing would be frustrating indeed. (It’s a tough enough assignment to meet up with a female who has the power to completely shut you out of her life by way of a shell—no wonder the male’s eyes are red—but even when the female is “open to the idea,” she is dressed in a negligee shaped like an army helmet. Thus the concave plastron was an essential part of God’s design.)

Since I intended to focus more on hibernation not procreation, that’s probably enough on that subject.

As the cold winds of winter begin to blow, we can only envy the hibernating creatures asleep far below, but I trust you’ll have many moments that bring to mind that line of Clement Clarke Moore’s:

“And mamma in her ‘kerchief, and I in my cap,
Had just settled down for a long winter’s nap.”
.

“Unsettled” Chapter 35: "The Foundation Was Poured in the Fall" will continue in the days ahead. Incidentally, in all the years we lived there, I never saw a single box turtle in our woods on the east side of the state.

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