Many-Storied Mountains: The Life of Glacier National ParkBeaumont, Greg
History
Many-Storied Mountains: The Life of Glacier National Park
Beaumont, Greg
Glacier National Park (Mont.); Natural history -- Montana -- Glacier National Park (Mont.)
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.
Public-domain text, read in full here on John Shaqi.
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