In many regions a fall of snow is followed by days of fair weather. During these days most of the snow melts; often the earth is almost free of one snow before another fall comes. In places of this kind the game have periods of ease. But in vast territories the snow comes, deepens, and lies deep over the earth for weeks. To endure long-lying deep snows requires special habits or methods. The yarding habit, more or less intensely developed, is common with sheep, elk, deer, and moose of all snowy lands.
The careful yarding habit of the moose is an excellent method of triumphing over deep snow. In early winter, or with the deepening snow, a moose family proceed to a locality where food is abundant; here they restrict themselves to a small stamping-ground,—one of a stone's throw or a few hundred feet radius. Constant tramping and feeding in this limited area compacts the snow in spaces and in all the trails so that the animals walk on top of it. Each additional snow is in turn trampled to sustaining compactness.
At first the low-growing herbage is eaten; but when this is buried, and the animals are raised up by added snow, they feed upon shrubs; then on the willow or the birch tops, and sometimes on limbs well up in the trees, which the platform of deeply accumulated snow enables them to reach. Commonly moose stay all winter in one yard. Sometimes the giving-out of the food-supply may drive them forth. Then they try to reach another yard. But deep snow or wolves may overcome one or all on the way.
During one snowshoe trip through western Colorado I visited seven deer-yards. One of these had been attacked by wolves but probably without result. Apparently five of the others had not as yet been visited by deadly enemies. The seventh and most interesting yard was situated in a deep gorge amid rugged mountains. It was long and narrow, and in it the deer had fed upon withered grass, plant stalks, and willow twigs. All around the undrifted snow lay deep. The limbless bases of the spruces were set deep in snow, and their lower limbs were pulled down and tangled in it. These trees had the appearance of having been pushed part way up through the snow. In places the cliffs showed their bare brown sides. Entire spruce groves had been tilted to sharp angles by the slipping and dragging snow weight on steep places; among them were tall spruces that appeared like great feathered arrows that had been shot into snowy steeps. The leafless aspens attractively displayed their white and greenish-white skin on limbs that were held just above the snow.
With a curve, the yard shaped itself to the buried stream. It lay between forested and moderately steep mountains that rose high. In this primeval winter scene the deer had faced the slow-going snow in the primitive way. At the upper end of the yard all the snow was trampled to compactness, and over this animals could walk without sinking in. Firm, too, were the surfaces of the much looped and oft trodden trails. The trail nearest to the stream passed beneath a number of beautiful snow-piled arches. These arches were formed of outreaching and interlacing arms of parallel growths of willow and birch clusters. The stream gurgled beneath its storm window of rough ice.
I rounded the yard and at the lower end I found the carcasses of the entire herd of deer,—nine in all,—evidently recently killed by a mountain lion. He had eaten but little of their flesh. Wolves had not yet discovered this feast, but a number of Rocky Mountain jays were there. The dark spruces stood waiting! No air stirred. Bright sunlight and bluish pine shadows rested upon the glazed whiteness of the snow. The flock of cheerful chickadees feeding through the trees knew no tragedy.
The winter food of big game consists of dead grass, shrubs, twigs, buds and bark of trees, moss, and dry plants. At times grass dries or cures before the frost comes. When thus cured it retains much nutrition,—is, in fact, unraked hay. If blighted by frost it loses its flavor and most of its food value.
During summer both elk and deer range high on the mountains. With the coming of winter they descend to the foothill region, where the elk collect in large herds, living in yards in case of prolonged deep snow. Deer roam in small herds. Occasionally a herd of the older elk will for weeks live in the comparatively deep snow on northern slopes,—slopes where the snow crusts least. Here they browse off alder and even aspen bark.
The present congestion of elk in Jackson Hole represents an abnormal condition brought about by man. The winter feed on which they formerly lived is devoured by sheep or cattle during the summer; a part of their former winter range is mowed for hay; they are hampered by fences. As a result of these conditions many suffer and not a few starve.
Wolves are now afflicting both wild and tame herds in Jackson Hole. Apparently the wolves, which formerly were unknown here in winter, have been drawn thither by the food-supply which weak or dead elk afford.