The eastern box turtle: too timid to visit
As I watched my collie plunge gamely into the Mississippi, I thought, “You know, it doesn’t look that wide. I bet I could swim that no problem, and so could she.” This came as a small surprise to me because, not knowing much about it, I’d always thought of the river as some kind of greater border. Maybe that started with the call letters.
One of the things I always thought I knew about radio stations is that their call letters all begin with “K” west of the Mississippi and “W” east of it—and, generally speaking, that turns out to be pretty much true, with a few conspicuous exceptions. The U.S. government established the Mississippi as the W/K line in 1923. Yet there doesn’t seem to be any particular reason for the line being there other than the obvious: The government wanted a system of organization to avoid confusion, and the Mississippi was considered the best internal demarcation by the time the decision was made. Because the eastern part of the U.S. was settled first, in the 19th century the country tended to be divided into north and south along an east-west axis such as the Mason-Dixon line. In the 20th century and down to the present, it’s more often divided into east and west along a north-south axis: the Mississippi.
And then there are the birds. I’m a fan of magpies, which are common where I come from in Alaska. I’d often heard that they only exist in the U.S. west of the Mississippi. Magpies are awfully clever birds so I wondered why they’d be stopped by a mere river, even a grand one. It turns out that they’re first recorded in the U.S. by Lewis and Clark in 1804 in South Dakota. While they don’t generally live east of the river—and more’s the pity for easterners, if you ask me—their habitat also begins well west of it. For magpies and many other species, the more important north-south axis is roughly the 100th meridian, which runs from the middle of North Dakota down through the middle of Texas, with the more arid, open parts of the country on the western side and the more humid, forested parts on the eastern.
So what does the Mississippi separate?
Some reptiles and some amphibians, says Jeff Briggler, a herpetologist with the Missouri Department of Conservation. “There are some that just don’t cross over big rivers. We have the three-toed box turtle on the Missouri side, and across the river on the Illinois side it’s called the eastern box turtle, with more brilliant shell colors and, typically, four toes. Unfortunately, these turtles are the kind people pick up a lot and move… And eastern collared lizards: that’s a western species that have not been able to cross over into Illinois—unless they’ve been introduced by individuals.”
As Briggler talks to me by phone he flips through books looking for species or sub-species that are thwarted by the Mississippi.
“Hmmm. Every time I get close to one there’s always one weird dot across the river,” he says.
“OK, in Missouri we have the eastern yellow-bellied racer”—that’s a kind of snake—“and in Illinois it’s the blue racer. And the ringed salamander reaches all the way into St. Louis and has not crossed the Mississippi yet. I doubt it will. Unless somebody picks them up and takes them across… And the bird-voiced tree frog is right across the Mississippi, and they have never been able to get across to the Missouri side—that we’re aware of.”
Still, in the vast animal kingdom, these are really the exceptions. We might as well face it: We—and I mean nearly all of us, bipedal and winged, feathered and furred and scaled—are a country of migrants, and no great respecters of rivers.
