Flight Lines: Transitions mark October, some apparent, some not
My butternut squash froze last weekend. Sunday morning I woke up to find my thermometer reading 34 degrees but it sits a few feet above the ground. At ground level, however, a distinctive hoary-white coating blanketed the grass next to the meandering squash vine, which also sported frost. Official thermometers are sited four to six feet above the ground according to WDAY meteorologist Daryl Richison, as does mine. That makes little difference to my squash which had its growing season come to a screeching halt Sunday.
October is the usual month for rapid and apparent changes in our local climate. Average temperatures drop precipitously throughout the period, daylength shortens noticeably, and snow usually falls. The polar jet stream is inching south and becoming apparent at lower altitudes. Trips that I flew this summer with relatively mild wind velocities are now showing winds up to 100 knots, greatly influencing arrival times.
The cue perhaps most perceptible to the casual observer is the changing color of tree leaves and their subsequent drop. Horticulturist Don Kinzler wrote a concise primer on how this occurs in the Forum recently. It turns out the yellows and golds in our elms and ashes are present year round; only to be revealed after the green-colored chlorophyll breaks down and stops masking the cartotenoid yellow pigment. Pretty cool stuff.
More evidence of the changing season is all around us if we’d take the time to notice. Soybean and corn harvest is running full throttle as those crops have ripened and dried. The mosquitoes which were so bothersome during the summer months have become an afterthought.
Many other insects are becoming less apparent too; they are starting to hunker down for the year. The group most of us are familiar with is Lepidoptera (moths and butterflies). Each species has evolved its own winter survival mechanism. A tiny few (think monarch butterfly) migrate. The rest overwinter in various life stages, egg, larva, pupa, or adult. This time of year the tiny insects actually produce glycerol to drastically lower their freezing point. That’s right, the antifreeze we use in our cars can be found in the tissues of overwintering insects. Without it, frozen water in their cells would act as daggers and quickly slice them into a mush.
Most amazing to me, mourning cloak butterflies—those blackish beauties with the cream-colored wing edges—overwinter as adults. They will find a crevasse in tree bark or a pile of leaves and settle in for the long cold dark. It will be the first butterfly next spring, emerging with a faded ragged appearance.
The past couple of weeks I’ve witnessed food caching, the storing of sustenance in anticipation of future scarce resources. Gray squirrels can be seen everywhere insistently pushing tree nuts and other foods into the earth. Piles of acorns in a tree hollow are the work of red squirrels. I’ve watched as blue jays, black-capped chickadees, and white-breasted nuthatches take seeds from the bird feeder and fly off with them. If followed with your eye, the birds can be seen stashing the seeds in the nooks and crannies of tree bark. We aren’t the only animal smart enough to lay away food for the winter.
The grasses and forbs are dying. At least it appears so. In truth, the energy these plants produced went into seed production; the means by which their genetic codes endure. For perennials, now is the time for survival. The sugars of the plants are being pushed into roots and buds to be stored until the signaling warmth of next spring brings another year of growth.
The ruby-throated hummingbirds that entertained us this summer and fall are long gone as are most neotropical migrants. Just a few cold-hardy warblers are still lingering—yellow-rumps and orange-crowneds. Soon even they will depart. Red-tailed hawks are passing by every day as are flocks of geese. Some of the more northern nesting birds that spend the winter with us have already arrived.
October is indeed a month of extreme transition. Perhaps this alteration, this tension, this continuous dynamic is why many of us claim fall as our favorite time of year. There’s certainly no staleness about it. As the northern hemisphere leans ever farther away from the sun (until late December when we begin the reversal), the ultimate source of energy wanes bringing wholesale changes to the landscape, to the wildlife, and to our lives.