The regular winter home of wild sheep is among the peaks above the limits of tree growth. Unlike elk and deer, the mountain sheep is found in the heights the year round. He may, both in winter and summer, make excursions into the lowlands, but during snowy times he clings to the heights. Here he usually finds a tableland or a ridge that has been freed of snow by the winds. In these snow-free places he can feed and loiter and sometimes look down on unfortunate snow-bound deer and elk.
The bunching habit of big game during periods of extreme cold or deep snow probably confers many benefits. It discourages the attacks of carnivorous enemies, and usually renders such attacks ineffective. Crowding also gives the greatest warmth with the least burning of fat fuel. The conservation of energy by storm-bound animals is of the utmost importance. Cold and snow make complicated endurance tests; the animals must with such handicaps withstand enemies and sometimes live for days with but little or nothing to eat.
Big game, on occasions, suffer bitterly through a combination of misfortunes. Something may prevent a herd reaching its best shelter, and it must then endure the storm in poor quarters; pursuit may scatter and leave each one stranded alone in a bad place; in such case each will suffer from lonesomeness, even though it endure the cold and defy enemies. Most animals, even those that are normally solitary, appear to want society during emergencies.
A deep snow is sometimes followed by a brief thaw, then by days of extreme cold. The snow crusts, making it almost impossible for big game to move, but encouragingly easy for wolves to travel and to attack. Of course, long periods separate these extremely deadly combinations. Probably the ordinary loss of big game from wolves and mountain lions is less than is imagined.
Some years ago an old Ute Indian told me that during a winter of his boyhood the snow for weeks lay "four ponies deep" over the Rocky Mountains, and that "most elk die, many ponies die, wolves die, and Indian nearly die too." A "Great Snow" of this kind is terrible for wild folk.
Snow and cold sometimes combine to do their worst. The snow covers everything deeply; then follows an unbroken period of extreme cold; the Ice King is again enthroned; the snow fiendishly refuses to melt, and lies for weeks; the endurance of most wild folk becomes exhausted, and birds, herds, and wolves perish. Similar calamities used occasionally to afflict our primitive ancestors.
Over the vast Northwest a feature of the climate is the winter-annihilating Chinook wind. This occasionally saves the people of the wilds when other relief is impossible. The snowy earth is quickly transformed by this warm, dry wind. In a few hours conditions become summer-like. Fortunately, the Chinook often follows a blizzard. Many a time at the eleventh hour it has dramatically saved the waiting, suffering birds and rescued the snow-buried and starving folk of the wilds.
The beaver and the bear are often benefited by the deep snows which afflict their wild neighbors. During the prolonged hibernating sleep, the bear does not eat, but he commonly needs a thick snowy blanket to keep him comfortable. The beaver has his winter stores on the bottom of the pond beneath the ice. These he reaches from his house by swimming beneath the ice from the house to the food-pile. If the ice is not covered by snow, it may, during a cold winter, freeze thickly, even to the bottom, and thus cause a starving time in the beaver colony.
Deep snow appears not to trouble the "stupidest animal in the woods," the porcupine. A deeper snow is for him a higher platform from which the bark on the tree may be devoured. Rabbits, too, appear to fare well during deep snow. This uplift allows them a long feast among the crowded, bud-fruited bush-tops at which they have so often looked in vain.
The chipmunk is not concerned with groundhog day. Last summer he filled his underground granaries with nuts and seeds, and subways connect his underground winter quarters with these stores. But heavy snows, with their excess of water, flood him out of winter quarters in spring earlier than he planned.