As if to make up for the days-long darkness of this last blizzard, the
peaks today wear snow plumes—long, graceful trails of white, curving up
into an ice-blue sky. Yesterday the snow-mad wind raced through the
forest. Today the motionless trees are cloaked in heavy, glistening
robes, the leafless aspen and young larch bent down.
Moderate snowfall helps many plants and animals survive the winter. For
ground dwellers it provides insulation from the wildly fluctuating
winter temperatures encountered east of the Divide, protecting the
hibernators and providing cover for the many small mammals that remain
active during the winter. Wind-swept ground freezes deep; but under a
mantle of snow life-sustaining heat is trapped, permitting many animals
to survive and allowing the work of decomposers to continue.
But this has been a winter of too much snow and too many temperature
extremes. The heavy snowpack has forced the sharp-hoofed deer to yard up
in great numbers; unable to range freely in deep snow, they are forced
into smaller and smaller confines where their numbers allow them to
break and maintain trails. But in time they exhaust the food supply.
Younger deer, unable to reach the increasingly higher browse line,
starve first. Then the does, heavy with unborn fawns, grow weak and fall
to predators. So the imprisoned herds dwindle quickly this year,
sometimes less than a kilometer from plentiful browse.
Deep snow is also death for many seed-eating birds. As they are unable
to scratch for food, their body furnaces quickly fail, and during a
night of cold wind their fluffed corpses drop into the snow.
Exposed to the noon sun, the snow surface thaws; when refrozen, it is
restructured to crystalline ice. If snow repeatedly thaws and freezes,
an ice barrier is formed, shutting off vital air exchange. Plants are
then subject to rot, and micro-animal life is smothered. Travel beneath
the snow is made more difficult for mice and shrews and they are
deprived of food and cover. Under such conditions their numbers rapidly
decline.
But while many starve in a winter of deep snow, others benefit. The
exposed traffic of small mammals is to the owl’s advantage. Foxes and
coyotes more easily run down rabbits and hares on crusted snow. Deer
and, to a lesser extent, wapiti and moose—their hoofs punching through
the snowpack—swiftly tire in deep snow and become helpless before cougar
or wolf, whose lighter weight is supported by the crust.
Grim as this winter’s toll becomes, enough will survive to begin the
process of renewal in spring. Last winter, a season of light snow, was a
time of hardship for predators. The deer remained strong, the wapiti
remote on high, windswept ridges, and the small mammals hidden.
Only the water ouzel, winter after winter, seems not to notice the
hardships of the season. Lord of his small world of open water, he sings
in February, wading and swimming his diminished stream to find a
never-failing supply of water insects and small fish. It is a voice of
spring—glad, wild, continual as the moving water—an incongruous song in
this winter-shrouded land.
But with the growing stature of the sun, the grip of winter softens. The
firs and spruce send their loads of snow sliding to the ground. Streams
begin to sing again and soon the lakes increase, the booming of
splitting ice breaking the silence of the valleys. Avalanches thunder
down the steeper slopes, carrying trees to the swollen streams. Rivers
hiss and rage, speeding the debris along. A spring that comes too
suddenly will bring flood to lower elevations.
Snow geese thread through the valleys, and ground squirrels tunnel up
through snow to find invasions of birds returning from the south. Soon
the three-petaled wakerobins appear, chasing the snowline up the ridges.
Glacier lilies and Calypso orchids are next, and with the shooting stars
spring arrives.
The melting snow releases a new group of animals to populate the
winter-thinned land. Up come chipmunks. Bears reappear. Young red
squirrels, helpless and blind, squirm in their nest holes. Hidden dens
rustle with pups and kits. Soon warm days will bring them out and the
business of learning to cope with their world will begin.
All life responds irresistibly to the growing strength of the Sun.
Cottonwood, willow, and maple come into flower and unfold new leaves;
green needle clusters spot the limbs of larches that in winter had
seemed lifeless snags among the other conifers. Beneath the soil of
prairie, meadow, and forest, in the mud of lakes and ponds, other life
stirs; armies of insects, spiders, crustaceans, amphibians, and fish
will strive to complete their life cycles against the formidable odds of
a predatory world.
Spring reaches higher up the mountains, the lowlands passing into
summer. Wapiti and mountain sheep follow the rising tide of succulent
browse up to the high meadows. In forest, grove, and meadow and along
the stream new fledglings appear—thrush, vireo, hummingbird, waxwing,
harlequin duck, bluebird, osprey, and flicker—as holes, nests, and
cavities brim with begging mouths.
In the alpine meadows, where snow overlaps the spring and winter follows
hard behind the summer, the growing season is short and the climate
unstable. Sensing the stronger light, flowers push up impatiently
through the snow and hasten into bloom. Pikas and marmots scurry and
sunbathe among the rocks of scree slopes.
Summer matures in ripening huckleberries, and the bears that grazed the
spring grasses now gorge themselves fat. Dry days of August bring
probing lightning, threatening the forests with fire.
Sweeps of beargrass reach their climax now in the highest meadows. In
dizzy succession wildflowers set seed. Fat and sluggish, marmots and
ground squirrels disappear beneath the rocks. The golden eagle must
search longer each day to find prey within its vast domain.
Autumn lingers in the valleys and on the flanks of low ridges. The
morning sun glints on hoarfrost, firing the yellow leaves of larch,
aspen, birch, maple, and cottonwood, and shines on the blood-red berries
of mountain-ash. Soon a night of killing frost will bring down the
corpses of insects and spiders by the millions. The reptiles and
amphibians, being cold-blooded animals, seem out of place in this
long-wintered land. Unable to maintain body temperatures appreciably
above their surroundings, they are the first to seek the protection of
hibernation, collecting in dens or burying themselves beneath the ooze
of pond bottoms.
Songbirds gather and leave the valleys. The harsh cries of jays sound
ominous now in the forest. Only the chickadees seem to ignore the long
tree shadows; their ceaseless conversations carry through the leafless
underbrush as they busily search for seed.
Velvet has gone to bone, and in these final noon-warm days the rut runs
through the land. It begins in the valleys in September with the
joustings of deer and moose and the buglings of bull wapiti puncturing
the forest silence. By November the higher meadows ring with the
collisions of bighorn rams who compete for ewes by smashing together
their massive, curled horns. On high slopes mountain goat billies
posture and swagger; head to tail, they circle, threatening each other
with dagger-like horns.
From Flathead Lake, 100 stream kilometers to the south, kokanee salmon
return to spawn in the clear, cold shallows of McDonald Creek. Gathering
bald eagles surround the stream, again and again lifting vulnerable fish
from pool and riffle. Perched by the hundreds along the stream course,
their white heads and tails glistening against the dark trees, they
stand out like lanterns strung for a banquet.
Now the stinging wind comes down from the peaks and shuts the lakes.
Life slows or sleeps. Ptarmigan, snowshoe hare, and longtail weasel, all
wearing winter white, seek shelter and food in a silent land where
spring and yellow lilies seem forever lost.
■
All life faces one ultimate challenge: to survive or not, to reproduce
or fail, to bring one’s kind to tomorrow’s sun or vanish forever. This
land is harsh. To survive in nature demands skill in the individual,
excellence in the species, and a chance from the environment.
[Illustration: The mink, a solitary predator associated with
low-elevation watercourses, preys on anything it can catch and
subdue.]