Where his sea of flowers began

The Westport Drumlin Natural Area is a tiny remnant of the Empire Prairie which – true to its name – once covered a large swath of Dane and Columbia Counties in southern Wisconsin. It also went by the more prosaic name of the Arlington Prairie. To get there from Madison, you ride northward out of town; in fact, the transition from urban to rural in this direction is amazingly abrupt, and in the blink of an eye you pass from subdivisions and Skipper Bud’s boat store to farmhouses and to fields luminous and pastel-coloured in early morning summer sunlight:
Early morning, River Road, Westport, WI
and you meander up and down along River Road, then finally turn off to climb the steep bank of the drumlin itself. The view from the top of the drumlin compensates for the effort of the climb:
View from Westport Drumlin
Wandering through the Area itself was actually somewhat humbling, because my untrained eye wasn’t really able to tell this relict prairie from the restored ones that are much more common. At times, evidently, there are guided walks, and someday I must show up for one. I did see a very attractive little grasshopper:
Grasshopper, Westport Drumlin
but didn’t see Westport Drumlin’s most interesting insect resident: the red-tailed prairie leafhopper, Aflexia rubranura. If you follow the link you’ll see that it’s not the most spectacular sight in the world, but it’s still pretty interesting; in large part because it sheds light on the history of the landscape. And not only on the landscape I’m living in now, but the one that I grew up in.

Both of which are connected by something I hadn’t heard of before starting to write this post – the prairie peninsula. Most of the North American prairie lies on the Great Plains, west of the Mississippi – at the hundredth meridian, as the song goes. However, there’s a sizable piece of it that pushes eastward, through southern Wisconsin, Illinois, Kentucky, Michigan, and Ohio, which have increasingly infrequent patches of remnant prairie, even to southwestern Ontario. This piece was called the “prairie peninsula” by Ohio biologist Edgar Transeau. Now, if you find a fragment of tallgrass prairie within the city limits of Windsor, Ontario, you may (a) be as surprised to learn it as I was, despite having grown up only a couple of hours away, and (b) ask the natural question of how it got to be there. Did it come into existence independently, due to changes in the local climate and migrations, or did much more prairie once come a lot farther to the east than it does now?

So it seems like the evidence points, in some though not all cases, to the latter answer, and a good part of that evidence is due to that nondescript little leafhopper and its relations. The story’s not simple; not even completely settled. It seems fairly certain that between 9,000 and 5,000 years ago there was an episode called variously the Xerothermic, the Hypsithermal, or the Holocene Climate Optimum, when summer temperatures in North America were some 1-2C higher, enough to make the area around the Great Lakes dry enough to favour prairie over forest. There may have, also, been episodes during the last Ice Age that favoured prairies to the east – and during one of those periods, Aflexia rubranura may have made its way to Manitoulin Island in Lake Huron, another place it can still be found. (Another Ohio biologist, E. Lucy Braun, thought there must have an another period of eastward prairie expansion before the last glacial period, so, more than 85,000 years ago. I don’t know what the current thinking on this idea is.) The leafhopper way of life makes it unusual for them to get picked up and carried long distances by winds, so if they’re found someplace, chances are they arrived there the slow way, following their food from point A to point B. Since as a rule they only eat one or a few kinds of plant, communities containing that plaint – prairie dropseed, in the case of Aflexia – must have existed all along the route at some point in time.

The prairie is so congenial to leafhoppers, in fact, that they have evolved whole new genera in it; there are more than 600 species of leafhopper which exist only within the North American prairie. I don’t know that this approaches the diversity of form and habitat of, say, the cichlids of Lake Victoria; but it seems very rich for the temperate zone. Despite their shy and retiring nature, though, there are some vivid-looking leafhoppers, such as this Graphocephala coccinea:
Candy-striped leafhopper
… which is not, in fact, endemic to the prairie, but can be seen even in urban neighbourhoods, as this one was.

In sum, though, the difference between what I could see and what was there to be seen is a reminder that, as far as nature goes, I’ve maybe progressed from looking at the pretty pictures to being able to tell (some of the time) what the illuminated letter at the top of the page is. That’s still a long way from reading the text.


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