Tuesday, December 20, 2011

The Winter in the Woods

Good morning Weathercock.  How did you fare last night?
Did the cold wind bite you and did you face up to the fright
when the leaves spin from October
and whip around your tail?
Did you shake from the blast and did you shiver through the gale?
                          ~ Ian Anderson, Weathercock, performed by Jethro Tull

Yellow-poplars, black locusts, and red maples, among others, ring the field, their naked branches a network of black capillaries against the winter sky.  A few solitary sycamores grace the arboreal gathering, standing bright white against this dark background.  In recent weeks the sycamores shed their leaves; they spent their summer shedding a layer of bark.  A curious phenomenon this exfoliating of bark, as yet unexplained.  Competing hypotheses range from a means of shrugging off parasites to allowing the continued production of carbohydrates after the loss of leaves.  (Patterson Clark, The Sycamore:  Tall, Pale, and Thin-Skinned, an Urban Jungle column that ran on December 1, 2011, in the Washington Post.)

Beyond the field are woodlands.  This is Sligo Creek Park which stretches for miles beside a creek that runs through suburban areas in the Maryland counties that border Washington, D.C.  A couple of weeks ago I came across a flyer published by the Friends of Sligo Creek, the volunteer organization that advocates for this park.  The flyer describes how the denizens of these woods and fields will cope with the rigors of the coming winter’s cold.

My favorite portrayal of animals in winter is pure fantasy conjured up by Kenneth Grahame and appearing in the third and fourth chapters of The Wind in the Willows, chapters titled, respectively, The Wild Wood, and Mr. Badger.  They recount Mole’s impulsive journey one winter afternoon into the Wild Wood seeking to make the acquaintance of the Badger.  Mole has tried to get Water Rat to arrange an introduction, “[b]ut whenever the Mole mentioned his wish to the Water Rat he always found himself put off.  ‘It’s all right,’ the Rat would say.  ‘Badger’ll turn up some day or other – he’s always turning up – and then I’ll introduce you.  The best of fellows!  But you must not only take him as you find him, but when you find him.’”

During the winter, the Water Rat (a vole, actually) spends much of time sleeping or drowsing before the fire or, on occasion, composing poetry.  Mole, on the other hand, apparently remains more active as the days shorten and the temperatures fall.  So, that fateful afternoon, Mole sets forth in search of Badger, leaving his friend napping or “trying over rhymes that wouldn’t fit.”  After entering the Wild Wood, Mole becomes frightfully lost and experiences the Terror of the Wild Wood.  At home, Rat, discovering Mole gone along with his new goloshes (a nice touch), knows immediately what his friend is about, and strapping on a pair of pistols and grabbing a “stout cudgel” sets out to the rescue.  Though he finds the terrified Mole, their escape from the Wild Wood goes wrong as night descends accompanied by a fierce snow storm.

As they struggle through the snow, Mole trips over something in the deep snow and cuts his leg.  Rat and Mole engage in a lovely verbal exchange about what kind of object may have caused this injury, capped by Rat’s growing exasperation at Mole’s inability to see the meaning in the finding of a door-scraper and then a door-mat buried in the snow.  This is Kenneth Grahame paying homage to Sir Arthur Conan Doyle’s Sherlock Holmes (Rat) and Doctor Watson (Mole).  (Annie Gauger explores this connection to Sherlock Holmes in The Annotated Wind in the Willows, 2007, p. 68-69.)
“Do – you – mean – to – say,” cried the excited Rat, “that this door-mat doesn’t tell you anything?”
“Really, Rat,” said the Mole quite pettishly, “I think we’ve had enough of this folly.  Who ever heard of a door-mat telling any one anything?  They simply don’t do it.  They are not that sort at all.  Door-mats know their place.”
Of course, once they dig into the snow bank, they find themselves at Badger’s door and manage to roust him apparently just as he was about to retire.  He, like the Water Rat, is passing his winter with much sleep.

It’s here at Badger’s home, in the cheery kitchen they enter off the “long, gloomy, and to tell the truth, decidedly shabby passage” that Grahame’s story captures so perfectly the joy of being safe, fed, and warm during the winter.
When supper was really finished at last, and each animal felt that his skin was now as tight as was decently safe, and that by this time he didn’t care a hang for anybody or anything, they gathered round the glowing embers of the great wood fire, and thought how jolly it was to be sitting up so late, and so independent, and so full; and after they had chatted for a time about things in general, the Badger said heartily, “Now then! tell us the news from your part of the world.  How’s old Toad going on?”
Ah, even the thought of Toad, whose misadventures form the core of the book, cannot diminish my pleasure at these three animals resting easily while the snow falls on the ground above them.

So how do animals actually deal with winter?  According to the flyer from the Friends of Sligo Creek, the responses are a creative mélange.  Some insulate their bodies against the cold by fluffing feathers, adding layers of fat, or growing thicker coats.  Some share body warmth by snuggling together.  Others pick up the pace of their activities, the increased activity generating warmth, while others slow things down, lowering their metabolic rates significantly (among the mammals in Sligo Creek Park, only the groundhog actually goes into the deep sleep of hibernation).  Of course, some just pick up and go, migrating to more appealing climes.

But of all of the methods that these animals have evolved, one depresses me, touching me like a cold hand on my spine.  The birds who stay and face the onslaught of winter deal with the cold primarily by shivering.

Surely not shivering.  At first, I could only deny the accuracy of this claim.  Rapid muscle contraction just didn’t seem a possible, reasonable long-term means of heat generation (thermogenesis) in response to low temperatures.  But the research literature says otherwise.  Most birds are homeotherms, that is, they seek to maintain a constant body temperature, regardless of the ambient temperature.  George C. West, University of Alaska, Fairbanks, professor emeritus of zoophysiology, in one of his early research articles on bird physiology wrote:
In winter in the north during the daylight hours, birds move about in search of food and general muscular activity produces sufficient heat to maintain body temperature.  However, at times of inactivity during the day or especially at night when birds are inactive, increased muscle tone and shivering appear to be the only methods available for producing heat.  (Shivering and Heat Production in Wild Birds, Physiological Zoölogy, April, 1965, p. 111)
Forty-six years later, this article continues to be a foundation piece in research on thermogenesis in birds.  For instance, José Eduardo P.W. Bicudo, et al., assert in their review of the literature (Thermogenesis in Birds, Bioscience Reports, April 2001), “Birds meet the bulk of their increased thermogenic needs in response to cold stress with shivering thermogenesis” (p. 182)  Their source for this statement is West’s 1965 article.

So, on those dark winter nights, as I pile another quilt on the bed and encourage the dog to curl up with the masters of the house, my pleasure is tempered with a bit of guilt that the avian inhabitants of the dark woodland shiver the night away.  Indeed, to the questions Ian Anderson asks of the metal weathercock, the living counterparts answer, Yes.
Did you shake from the blast and did you shiver through the gale?

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