Forecasting Winter Severity Using Signs from Nature

The other day I spotted a hornet's nest hanging from the branch of a small witch hazel tree. It had been cold recently and knowing the Bald-faced hornets that built and used the nest during the summer abandon it after the first big frost, I decided it was worth collecting. As I approached, I remembered an old wives' tale that claimed you could predict the severity of the coming winter with a hornet's nest. The saying goes: if the nest is close to the ground, the winter will be dry, but if the nest is high in the trees, then snow will pile deep.

Folklore has passed down many methods of prognostication. You are probably familiar with the midwinter ritual of dragging a poor rodent from its den to see if it notices its shadow. But did you know that Alaskan Indians check the position of bears in their dens to predict the severity of their winters? Not a job I would be willing to do. According to the Kutchin Indians, bears will lie close to the den opening when the winter is to be mild, but dig deeper in if the winter is to be severe.

Now you might want to check out bear dens, but another tribe has a less risky technique. The Koyukon Indians search out hare tracks in the season's first snowfall. If the tracks are wide, that means the hares have extra hairy feet, telling of a cold and wet winter. And perhaps this is true, but has anyone ever bothered to check such wives' tales?

Well, yes indeed they have. You've perhaps seen the caterpillar known as the woolly bear. It is the larva of the Isabella tiger moth, a somewhat non-descript beige moth. Legend has it that woolly bears foretell the severity of the coming winter. If the orange/brown band around its midsection is wide, the winter will be mild; if the band is narrow, get out and split extra firewood or buy a new snow shovel, because, a harsh winter is in store.

In 1948, Charles Curran of the American Museum of Natural History began an 8-year study of the caterpillars. He dutifully collected and measured dozens of these little buggers each year. For years he found that the reddish segment accounted for about one third the body length of the caterpillar. The corresponding winters were mild, seeming to confirm the folklore.

During the eighth year's collection however, Curran found two populations of caterpillars just about 100 feet apart; one predicted a harsh winter and the other a mild one. Now either this was going to be a terribly unusual weather pattern or the myth of winter prognostication by means of caterpillar was busted. With this conflicting data Dr. Curran ended his study. Did he give up too soon?

Another more recent study by entomologists have determined that older woolly bear caterpillars tend to have wider bands than young ones. Therefore, if the previous winter ended early, caterpillars would emerge early, and would be older in the fall than if the winter had lingered. Trouble is, this tells about the previous winter, not the upcoming one.