Naturespeak A naturalist's view of the world

October 22, 2009

You Go, Bear!

Filed under: Uncategorized — wykes @ 9:01 pm

Well, the official 2009-10 Woolly Bear Weather report is in.  Before you dismiss my results out of hand, allow me to explain that my research was performed under carefully controlled clinical conditions and made use of time-tested techniques. I do not take this task lightly. After-all, road commissions need to know how much salt to order and long underwear companies need to predict their upcoming sales. Our very lives depend on the accuracy of such a report. History has proven that the traditional methods of weather prognostication, such as measuring the thickness of the wall on a hornet’s nest, calibrating the bushiness of a squirrels tail, or judging the  intensity of pain emanating from a corn, are bogus. No, only Woolly Bear caterpillars should be considered as  long-term weather prophets. According to the accumulated wisdom of the Woolly bears, therefore, the 2009-10 Woolly Bear Winter Forecast Number is……….drum roll, please…….brrrrrrrrrrrrrrrrrrrap! 5.2!

Please allow me to explain the science behind this incredible figure. Don’t worry, I’ll simplify the complicated stuff and give it to you straight. In the ‘bearcast biz. 5.0 means average winter conditions – you know some snow, cold air, one dead sparrow, etc. Any number higher than 5.0 means above average winter conditions – like some more snow, a few more colder days, a small pile of dead sparrows, etc. The scale only goes up to 12, which would indicate a winter in which every single sparrow freezes to death. Numbers lower than 5.0. of course, point to balmier conditions with less snow, fewer cold days, and increasing numbers of sparrows dying from heat exhaustion. A “0” on the bearcast scale means massive flooding, brush fires, and windrows of tiny cooked sparrow carcasses lining the melted asphalt streets. Sparrows do not like the ‘bearcast for obvious reasons. At any rate, a number like 5.2 means “slightly colder than normal with a good chance of chilled sparrows.”

Woolly Bear Caterpillars, the fuzzy larvae of the Isabella Tiger Moth, know a thing or two about winter. They overwinter as larvae and finish their growth cycle the following spring. Their distinctive black and orange woolly coats serve to protect them from predators (they roll into a ball when threatened) and provide some insulation against chilly fall temperatures.  Your typical Woolly Bear is black at each end and orange in the middle, but individual ‘bears vary in the width of that orange band.  Long ago it was “discovered”, by people missing several teeth,  that wider orange bands foretold cold winters and narrow ones indicated warm winters. “Them that have them big orange sweaters,” it was widely reported, “are gitt’n ready for a right nasty winter.” Thus the source of the ‘bearcast tradition.

On a bright sunny afternoon not so long ago I decided to tally up an average of Woolly bear sweaters and see what they foretold. I simply counted the number of body segments bearing orange bristles and then averaged them out. There are a maximum of (about) 12 body segments per ‘pillar, so theoretically the counting could run from “o” up to “12”, but the actual range is between 4 and 6 (average of 5).  I examined 9 individuals which ranged from a low “normal” number of 4 to a high of 6 orange segments. Some segments were half covered and were recorded as such. The individual pictured above was a 6 bander  (go ahead and try your skills out). The population averaged exactly 5.2 orange segments – thus the winter forecast number.

Just for laughs, I also attempted to record the average speed of the caterpillars. Woolly Bears can really burn up the grass when they are clipping at top speed from one side of a field to another. According to my calculations they were moving at the rate of exactly .037 mph. I imagine that they could attain higher speeds if shaved and will attempt a future experiment once I figure out how to shave them (they have 16 armpits!).

Before you rush out to get those long undies, I feel the need to tell you one more thing. Although my data set consisted of 9 caterpillars, I actually encountered 10. I threw out the results of the tenth beast because it was abnormal and, besides, it would have skewed the results. This individual, pictured below, was all black. According to this one brush fires and charred sparrows are in our future. In other words, there would be no winter at all! I had a bad feeling about this bizarre individual. My sense was highlighted by the fact that it had a milkweed bug riding shotgun on it’s back. The little guy was holding on for dear life as it’s furry ride chugged across the trail. That was just plain strange. As far as I know, there are no folklore interpretations to cover such an un-natural partnership. If there is, I’m sure it would require the loss of a few more teeth and lives of a few more sparrows.


  1. I am in the library today reading your woolly bear post and have received several stern looks as I simply had to laugh out loud! I think I am rapidly becoming your biggest fan! Thanks!

    Comment by Ellen — October 23, 2009 @ 2:45 pm

  2. Hilarious – this has to be one of the funniest blog posts I’ve read in a very long time! Your speed calculations brought back long-forgotten memories of childhood woolly bear races up strings we had tied on the back of an old ladder. Thank you!

    Comment by Holly Austin — November 3, 2009 @ 6:00 pm

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