Nature Notes

Vol. XI May - 1933 No. 3

Why Do They Waken?

When the pulse of spring begins to quicken in the High Country, long after the drowsy haze of summer has softened the valleys below, the alpine plants and animals know that their hour has come. As we watch the vernal awakening of life year after year we are led to wonder what secret signal is given to the sleeping actors that they may know the stage is set for the brief drama which they will enact before the snows of autumn set in. In seeking an answer to this question we consider a half dozen factors which might be instrumental in rousing the plants and animals from their long winter sleep.

As far as plants are concerned the most powerful influence is an increase in temperature with a resulting release of water from the melting snow. During the freezing weather of winter the soil underlying a thick blanket of snow is, curiously enough, lacking in sufficient moisture to promote plant growth, the vital water being locked up in the form of tiny crystals of ice. In the brilliant sunshine of June and July a host of rivulets from the melting snowfields trickle over the hillside and saturate the soil to the limit of its capacity. Then the fleshy roots of such plants as the Avalanche Lily and the Hellebore swell with renewed life and ram their tightly curled heads up to the light of day through several inches of snow. Again, it might be suspected that the release of a burden of many tons of snow would stimulate the early sprouting of vegetation, but we know that plants are capable of exerting a tremendous pressure of their own accord, sufficient at times to break thru rock itself, and thus would not be greatly restrained by such a substance so previous as snow. The action of sunlight is a factor only insofar as it tends to melt the snow, since we observe plants germinating in total darkness as readily as in light. Nor is the factor of time, or season of great significance in this respect, for in some years the emergence of plants in certain areas is delayed for as much as six weeks by unusually cold weather.

In the awakening of animals, however, we must consider the element of seasonal change of paramount importance. Those furry beings in whose veins the pulse of life beats steadily, though feebly, throughout the winter become restless about the time when their stored up layer of fat, or their store of foodstuffs, is nearly exhausted. Regardless of the depth of snow or the chill of the air we find the marmot and the cony coming out to blink their eyes in the long light of early spring. True, they may survey the expanse of snow and decide that the table is not yet laid for breakfast; tighten their belts and go below again. But sooner or later the pangs of hunger become acute, especially after the nesting time has arrived and a new lot of mouths are crying to be filled. Then we find the squirrels and the marmots tunneling out of the snow and making long foraging expeditions to some windswept ridge greening with early vegetation, or to clumps of alpine firs where the cones of last year are nipped off with chisel teeth and the seeds withdrawn. On a trip up the slopes of White Horse, in the Cascade Range, as early as May 15 a pair of marmots were observed moving about at an altitude of 6,000 feet on a field of snow that was to remain unmelted for several months. The upper slopes of Paradise Valley are, in early summer, dotted with the well-worn openings of many marmot burrows, and from these tracks lead out to nearby vegetation. Behind the Guide House a ground squirrel last June had been entering a tunnel leading down through three feet of snow to her nest below. It is unlikely that the sun's warmth could penetrate an insulating blanket of snow to arouse an awakening response in the sleeping animals below, hence we must conclude that it is hunger brought about by the passage of time which awakens the alpine animals, as it is moisture, brought on by an increase in temperature which awakens the plants.

Victor Scheffer,
Ranger-Naturalist, 1932.

marmot burrow in snow

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