Skunks and Martin Luther

February 6, 2017

Grant Avenue smelled of skunk this morning from Lee almost all the way to Finley. I wonder whether Aldo Leopold would have thought differently about skunks if he’d lived in Downers Grove in the 21st century. He opens A Sand County Almanac with “January Thaw:”

Each year, after the midwinter blizzards, there comes a night of thaw when the tinkle of dripping water is heard in the land. It brings strange stirrings, not only to creatures abed for the night, but to some who have been asleep for the winter. The hibernating skunk, curled up in his deep den, uncurls himself and ventures forth to prowl the wet world, dragging his belly in the snow. His track marks one of the earliest datable events in that cycle of beginnings and ceasings which we call a year.

Downers Grove is an exceptionally skunky town, and while there has been an uptick of skunk activity as it warmed up the past few weeks, I am not sure the skunks ever did lie down to sleep for the winter this year. Hibernation for a skunk in the Chicago region in 2017 may not be the hibernation of a skunk in central Wisconsin in the 1940s. We know that the wildflowers Leopold tracked at his shack on the Wisconsin River bloom earlier now then they did when he was making notes. It’s probably reasonable to expect the skunks to behave differently as well, and all the more so 100 miles south of the shack and 60 miles closer to Lake Michigan.

It was about 25 degrees when I got to the gate, partly cloudy, ten minutes past five. I had thought I’d do a short walk today so I could get into work earlier, but I was struck by a desire to park my bike at the Big Rock Visitor Station and walk the long way around to work, come in by foot. I recalled Martin Luther, who is said to have made the statement that he had so much to do, he had to start his day with three hours of prayer. I have so much less to do than Luther did. He set about reforming the church: today I had meetings and some oak research to conduct. I could surely spare as much time for meditation as Luther could.

I walked what may be my favorite section of the east woods, the rolling moraine to the east of the Big Rock station, with the depressional woods off to the north and topography reminiscent of the driftless area. I stumbled off the trail and meandered down along the edge of the standing water. The soil is frozen solid, crunchy and ragged from heaving with every freeze and relaxing with each thaw. The leaves are frosted in place, and a massive dead log emerges from the water. There’s no sound: I think I hear a bird, but I realize it’s my nose whistling. Warblers will be back in a couple of months.

I followed the road back to the trail, crossed over to the hilltop at the eastmost turn in the trail and down through the bur oaks above Parking Lot 10. One oak struck me this morning: it’s a bur oak near the bottom of a slope, bristling with adventitious shoots clustered around the scars left by fallen lateral branches. There wasn’t another tree like it in sight, and I didn’t see another one on my walk today. I doubt this is a response to some mistreatment visited on this tree in particular. It is perhaps a heritable predilection to resprout in response to injury. Is it adaptive here? Perhaps not, but we should know in a few generations. Oaks carry a lot of variation in each population. They are so highly heterozygous that the progeny of even a first-generation cross between populations of a single species may carry a great proportion of the range of variation of the parent populations. This works if the variation you care about is governed by a lot of genes and the parent populations are heterozygous for a good number of them. This may not be the only way it works, but it’s sufficient, and oaks certainly are configured this way.

Further on in the oak collection, I found a marcescent oak I hadn’t noticed last month. It is a small Hill’s oak (Quercus ellipsoidalis E.J.Hill) planted from seed 25 years ago, accession 204-92. This tree, like one of our marcescent black oaks, is collected from northern climates, this one from Winneshiek County, Iowa. Like the bristly shoots of the bur oak that passed earlier in the morning, these marcescent leaves may reflect past adaption, or they may a juvenile attribute that is neither adaptive nor particularly maladaptive. I begin to doubt, however, that the variation within species has much if anything to do with climate of origin. We’ll see.

Much of the trail to the west of the oak collection was dominated by bur oaks, with some red oaks and ironwood (Ostrya virginiana). One oak confused me: it had the appearance above of being a bur oak, but the bark was much more shallowly ridged. I was guessing in fact that it was a black walnut, but I couldn’t find any leaves beneath to support that. I think the East Woods would be as good a place as any to study hybridization between bur and white oaks. The problem would be sampling: how to get to the canopy and sample those leaves? I’ve always made do with sampling shoots ca. 15 feet up at the most… this may be the year to get serious about canopy leaves.

I passed the Carex lacustris marsh, Marlin Bowles’s dry prairie, Meadow Lake, the Children’s Garden and the groundcover garden and got to my desk 20 minutes earlier than I had thought I would. It’s 8:15 now, just 3 hours into my morning, and, Martin Luther and the skunks, I’d better get back to work.

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