_Producers_ are the green plants at the base of the food pyramid,
manufacturing food for the animals of the alpine community. The
_biomass_ (total weight) of each level of the food chain is ten
times (more or less) the weight of the stage above it: 1,000 kilos
of green plants will produce only 100 kilos of primary consumers.]
[Illustration: Great horned owls are the nocturnal equivalent of
Cooper’s hawks and goshawks in the low-elevation forests of the
park. Large and powerful, they are capable of taking prey as big as
skunks. This young bird, disturbed on its day roost, clacked its
bill and fluffed its feathers in a menacing manner.]
[Illustration: The only sizable mature stand of ponderosa pine found
within the park is along the North Fork truck trail. A scattering of
old ponderosas growing at the lower end of Lake McDonald suggests
that at one time ponderosa forests were more extensive in this
region than at present.]
[Illustration: A black bear near treelimit. Bears will eat almost
anything, from ants to carrion, grass to garbage. Color phases
include brown and blonde bears. Unlike the larger, more aggressive
grizzly, which ranges out onto the plains, black bears are strictly
forest creatures.]
[Illustration: The water ouzel, or dipper, a creature of fast
mountain water, is admirably outfitted to cope with its demanding
environment. Stubby wings, chunky body, short tail, and oily plumage
allow it to walk under water, where it scavenges for aquatic insect
larvae and small fish. In flying up- and down-stream, ouzels never
shortcut but follow the winding streamcourse.
As long as there is open water, the dipper suffers no hardship from
the mountain winter. Then, when the land is shut down and lakes are
frozen over, this little bird carries on in its mountain-stream
habitat, plunging into the cold water to find food, and pausing
occasionally to sing.]
[Illustration: Ouzels construct their nests of living moss on cliff
faces or ledges where constant spray keeps the moss moist. At
fledging, the four young of this nest in Avalanche Gorge tumbled one
by one into the torrent below, to be collected by the adults in
quieter water downstream. Within a day they appeared to have
mastered the underwater gymnastics and were feeding on their own.]
[Illustration: From their lowland wintering grounds, wapiti move up
to higher elevations in spring. Summer range in the park is
abundant, but winter range is limited; as a result, wapiti have a
tendency to increase their populations beyond the carrying capacity
of available winter range. In a severe winter many starve. But in a
balanced ecosystem such loss is not waste, for the carrion helps
sustain scavengers; it is an important initial food source for bears
emerging from hibernation.]
[Illustration: Cedar waxwings nest in moist areas of low valleys
where fruits and berries are abundant. Although they also subsist on
insects (which they can capture on the wing), their weakness for
fruit is so pronounced that the birds will sometimes gorge
themselves until rendered incapable of flight.]
[Illustration: The Columbian ground squirrel is found at all park
elevations, from prairie to alpine meadow. Hibernation occupies
almost three-quarters of its five-year lifespan. Unlike other park
ground squirrels, it lives in colonies. Although not as tightly
structured as a prairie dog town, the association is beneficial to
all members in that danger is readily detected.]
[Illustration: The tundra community is encountered above Preston
Park on the Siyeh Pass trail. Mt. Reynolds, a classic example of a
horn, dominates the distant Logan Pass area.]
[Illustration: Camas blooms in the prairie community along the Red
Eagle road. An important staple, camas bulbs were gathered as food
by Indians.]
Conspicuous also are many insects—including grasshoppers; flies; ants,
wasps and bees; butterflies and moths; bugs; and beetles—which fulfill
important roles as herbivores, carnivores, and scavengers while also
acting as pollinators for flowering plants and providing an abundant
food source for other animals.
Below the ground are the tunnels. Burrowing is an important means of
survival on the open prairie, and life underground is extensive. Some of
the animals are rarely seen—the northern pocket gopher, for example,
with a diet of underground insects, grubs, worms, and roots, spends most
of its life tunneling just below the surface. Others, like the badger,
leave their burrows during the day to dig for rodents. Most conspicuous
of the burrowing animals in the park’s grasslands is the Columbian
ground squirrel. Its alert upright stance has earned it the nickname
“picket pin.” When danger approaches from the air or on land, its shrill
alarm whistle passes the warning to others of its kind.
Where prairie and forest meet, a never-ending struggle for dominion is
waged. The isolated patches of prairie that dot the North Fork Valley
near Polebridge hold the great forest of the park’s northwest region at
bay.
This broad valley, floored with coarse glacial outwash and terraced
downward to the deep channel of the North Fork River, presents a graphic
battleground between grass and tree. Lining the upper terraces, from
which they glower down on the dry, well drained grass flats like a line
of warriors, are the Douglas-fir, western larch, and ponderosa pine.
Seedling trees continually invade the prairie. But most perish early,
their shallow roots no match for the extensive root systems of the
fast-growing, moisture-greedy grasses. If encouraged by a series of wet
summers, however, the young lodgepoles quickly gain stature. They had
made significant inroads at Big Prairie when the disastrously dry summer
of 1967 killed most of these 15-year-old pioneer trees.
These North Fork grasslands and the immediately surrounding lodgepole
pine forests are an important spring range. Deer, wapiti, and
grizzly—and, in the wetter areas, moose—graze or browse here. And here,
low on the western slopes of the Livingston Range, are the park’s only
stands of ponderosa pine, a tree that prefers warm, dry habitats. As a
result, at low elevations it often merges with the prairie community.
Groves of aspen colonize the eastern prairies in areas where there is
sufficient water and protection from wind. These aspen parklands are
important havens for animals. Wherever two differing communities
interact, a phenomenon known as “edge effect” occurs. Here wildlife
exists in abundance; the animals that favor forest cover mingle freely
with those that prefer open areas. Aspen groves—supporting grasses,
herbs, and shrubs beneath their thin canopies—are favored haunts for
grouse, varying hare, deer, and wapiti, all of which find among the
trees abundant food, shelter and concealment. Populations of insects,
small mammals, and birds, which are high for the same reasons, attract a
wide range of predators.
Isolated aspen groves are characteristically dome-shaped. Because aspens
are capable of reproducing themselves vegetatively, the grove slowly
expands outward from the parent tree. As a result, most of these groves
are either exclusively male or exclusively female.
Since quick-growing aspens provide a bountiful food source for beaver,
streams near these trees are often dammed by the rodents flooding
lowlands and creating additional habitat in the form of willow flats.
Another “edge effect” is established, attracting animals found near
water. Waterfowl, marsh birds, moose, mink, muskrat, skunks, amphibians,
and many others find such areas to their liking.
■
Before the appearance of the white man, these eastern prairies were a
paradise for animals. Once, on the summit of Rising Wolf, light-headed
from the climb and the view of endless prairie, I fancied that I saw
that vast, undisturbed animal panorama spread before me.
Principally there were the bison, darkening the uneven land. Pronghorn
bands flashed white on ridgetops, and moose moved through the long
fingers of willow that extended eastward with the rivers. Caribou and
wolves inhabited the shadows. Among vast cities of prairie dogs, swift
fox and grizzly roamed. There were the clamorings of sandhill crane, and
white clouds of trumpeter swans.
This land, endowed with a wealth of wild grass, wore its wilderness
well.