  Over Going-to-the-Sun RoadI like to begin with St. Mary, a lake the whitecaps love to run. From the far passes the several winds gather and collect, arranging long lines of white waves for the race downlake. Past the purple scree of Mahtotopa and Little Chief they go, white as the headdress of Going-to-the-Sun Mountain, colliding, collapsing along the promontory snares about the Narrows. Onward they press, spreading out and setting sail for the straight rush to the final shore where a line of cottonwoods sings with a sound like applause. Across the lake the timbered ridge starkly contrasts the finger of prairie that claims the north shore. This is a flower-glad place, a meeting-ground for mountain and prairie plants. Along the road the grassland holds the conifers back, allowing only scattered clumps of aspens. Finally, at Rising Sun, beneath the shadow of Goat Mountain, the prairie ends and wind-seasoned Douglas-firs announce the coming forest. There’s excitement now, with the prairie heat gone, the wind scent raw with fir and high meadows, honed by waterfall and tall, dank rock. Our mountain thirst is never extinguished, and a road that tightens down to cliff face and sudden turn brings back to our blood the ancient need to go to the highest place. There is sword-edged Citadel, and the snow-flanked spike of Fusillade holding court like a queen in this valley of peaks; then the dome of Jackson and the Gunsight notch. Our eyes are kept high, transfixed at last by looming Heavy Runner and the distant promise of Reynolds. Looking for mountain goats, we scan the walls around the sweep of Siyeh Bend, catching a glimpse of the trail that crosses the scree to hidden Piegan Pass. Beargrass heads lean out above the road like old men conferring on the view. The purple trumpets of penstemon crowd the rocks, and spots of Indian paintbrush lead like a blood-trail to the higher slopes. Intoxicated now, feeling the fresh full force of the wind from Logan Pass, we race on. We hardly notice the struggle of the forest in Reynolds Creek far below, how it thins and loses strength in its own hard climb. We sweep past it on the broad magnificence of this pass. Level but a moment, the road dips to a shelf on the headwall above Logan Creek and swings over the great sculptured cliff of the Garden Wall. For several kilometers this masterpiece of a road glides down a constant grade, squeezed between rock face and space, twisting into tight drainages—a road for storm lovers, wet with spray and snow-seep, its quick turns concealing sudden winds. Mighty, snow-robed Heaven’s Peak appears, taking our attention from the Pass-group mountains and the hanging valley Not until we have passed the Loop and are moving past the blackened snags of a recent burn do we realize the stature of this forest. The long road down will take us into a valley much deeper than any on the eastern side. Near Avalanche Creek are trees we have seen nowhere else in the park—giant western redcedars, western hemlocks with their nodding tops, monstrous black cottonwoods with bark so deeply furrowed that it looks hewn by hatchet. We take a long ride down the valley, past the low pyramid of Mt. Stanton, final peak in the Livingston Range. Near the outlet end of Lake McDonald, birch and aspen again appear in numbers, and the road enters a crowded stand of lodgepole pine. Our memories cluttered with mountains, waterfalls, and snowfields, we do not quite realize the significance of this 80-kilometer journey. We have crossed the boundaries of several different plant-and-animal communities, spanning a range of climate that would be encountered on a 5,000-kilometer north-south journey at sea level. At first glance the various trees, wildflowers, and animals seem randomly distributed, scattered about like the distant mountains. But mountainous terrain represents an organized high-rise approach to life. From the lowest, most protected valley to the highest wind-and-ice-cut summit, the life-forms align themselves, each according to its own climatic tolerance. Here too can be seen the great cycles of nature: fire and regrowth, the building of soil and its erosion, the incessant duel of the eaters and the eaten. In the following sections we will spend some time in these various communities, from prairie to tundra. Groves and Grasslands: The Prairie SeaThere is something about spring on the prairie that gets me up before dawn. I like to watch the seasons change their guard over the landscape, from the wintry cold of pre-dawn dark to the spring-scented morning air to the hot summer-foretaste of the noon May sun. Hoarfrost surrounds these patches of pasqueflowers, blue goblets on downy stems. On this windless night, frost has formed everywhere, reclaiming for a time its vast winter range, sparkling over the green handiworks of spring. But the god of the growing grasslands is the sun, and it now proclaims itself, stretching out to make the mountains shine. With its assault the frost collapses, becoming bright beads on grass tip and leaf joint by which a beetle might refresh itself. Spring is best perceived ant-level, at its ground beginnings, where the bright yellow-green tips of new grass shoots reclaim the winter-blighted land. I look closely at a drag line of spider silk; a necklace of dewdrops slides down, collects to a moment’s greatness, in which I briefly see a curved horizon, the morning sunburst, and myself, before it falls away. Getting up from my prone position, my belly damp from the prairie earth, I startle a whitetail jackrabbit; bounding high, it zigzags off. The commotion disturbs a distant badger, which faces about from its diggings to confront danger in whatever form it might take. It swings its snout to scent the air. Somewhat uncertainly, it returns to the business of hunting, then hesitates, swings about once more and waits, myopic, patient. Satisfied at last, the spurt of the now distant rabbit lost in its brain, the creature snorts a defiance at the mystery and resumes its morning gopher hunt. Overhead a marsh hawk skims past, its flight erratic as a butterfly’s. Far away a magpie rattles at the passing hawk and takes flight, briefly flashing black and white.
Here on the prairie, as in every plant-and-animal association, the ancient drama repeats itself over and over; the distant tundra is a drastically different stage with different actors, but the cycle is the same. Life depends upon the interaction of all its The secret of life rests in the wonder of photosynthesis. Only green plants can manufacture food from the earth’s raw minerals. This is the vital first step upon which the great pyramid of animal and plant life is built. Using energy from the sun, green plants combine water and carbon dioxide to synthesize sugar, and give off oxygen as a by-product. The caterpillar takes its energy from the plant tissue, converting to protein the sugar and minerals in its body. The caterpillar is then food for a spider or other predator. A yellow warbler may take the spider and in turn be ambushed by the prairie falcon. Thus the energy produced by the plant travels through the food chain. When the prairie falcon dies, scavengers—including insects and other invertebrates, birds, and mammals—redistribute its wealth among themselves; the rest is decomposed by bacteria. Thus, eventually, the nutrients on which the plants depend return to the soil. When we look at any living organism, whether it is plant, herbivore, carnivore, parasite, scavenger, or decomposer, we are soon made aware of its associations with other living things, each puzzle piece leading us to another and another. We begin to see a picture whole—the fox, meadow mouse, grasshopper, bunchgrass, and sparrow hawk—all interlocked. Geologically speaking, grasslands are a recent development. As the Rocky Mountains were being uplifted, the prevailing warm, moist climate began to change. The rising mountain mass intercepted moisture-laden winds that blew in from the Pacific, creating a rain shadow that lengthened eastward as the mountains rose higher. A continental climate, characterized by severe winters and dry, wildfire summers gradually took shape, extinguishing the great forests that had grown across the continent’s interior. Herbaceous plants, which had been evolving amid the forests, inherited the land. Unlike trees, grasses die back to the ground each winter, hoarding their life-germ beneath the protecting soil. Growing not from the tip but from the joints, grasses regenerate quickly after fire or grazing. Suspension of the normal metabolic processes enable the grasses to go dormant and thus survive periods of severe heat and drought. Although the great prairie sea washes up against Glacier’s eastern boundary, with estuaries probing into the mountain valleys on the drier, south-facing slopes, the grassland community comprises less than 5 percent of the land area of Glacier National Park. This includes the puddles of prairie west of the Divide that interrupt the dense coniferous forests along the North Fork of the Flathead River. From the pasqueflowers that bloom in early May to the asters and goldenrod of September, these summer-long gardens of grasses and flowers lean with the wind. Here are timothy, oatgrass and the bunchgrasses—rough fescue, bluebunch fescue, and bluebunch wheatgrass. Among the grasses bloom bitterroot, blue camas, lupine, gaillardia, balsamroot, cinquefoil, sticky geranium, and wild rose. continued on p. 68 The Forests of Glacier From the lush redcedar-hemlock forest in the McDonald Valley to the subalpine fir, whitebark pine, and Engelmann spruce struggling for existence near treeline, the forests of Glacier reflect the conditions of temperature, exposure, soil, and drainage prevailing; and each forest has its characteristic association of understory trees and shrubs, herbaceous ground cover, and vertebrate and invertebrate animal life. Life Zones Many physical and climatic factors determine the range of Glacier’s plant-and-animal communities. Boundaries between communities are seldom sharply defined, but rather merge together in broad zones of transition. With elevation gain, average daily temperature drops at the rate of 5° per 900 meters. Precipitation, wind velocity, and evaporation loss increase. Soil thins. These factors, along with others such as fire frequency, north or south exposure, and availability of moisture, combine to determine the range of each community. In the forest community below 1,800 meters, Douglas-fir, lodgepole pine, and western larch predominate. In the valleys, Engelmann spruce and subalpine fir are found. The somewhat lower and much better watered western valleys of the park support western redcedar and western hemlock. Treeline is the upper limit to which the tolerances of trees to environmental conditions permit them to grow. Because there are so many controlling factors (wind, temperature, exposure to sunlight, snow cover, etc.) treeline in the diagram is only approximate. In Glacier it averages 2,000 meters. Avalanche chutes or sheer cliff walls may suppress it to below 1,500 meters; on protected slopes it may be as high as 2,150 meters. At the eastern edge of the park below 1,200 meters, the forest gives way to the prairie community, composed mostly of soft-stemmed plants adapted to the conditions of low precipitation that prevail here in the rainshadow of the mountain range. Clumps of aspen, found in the prairie in sheltered spots, occur here in the transition zone between prairie and forest. A Mountain Profile This diagram represents the eastward-facing slope of a hypothetical mountain near the eastern boundary of Glacier National Park. Its life communities are somewhat different from those of mountain slopes at the western edge, chiefly because of the differential in annual precipitation. Illustration: Here, above approximately 2,750 meters, in a realm of ice, snow, and barren rock, there is little life. Alpine tundra Below 2,750 meters and above 2,000 meters, depending on other factors such as exposure to sun and wind and steepness of terrain, exists the alpine tundra community, with vegetation similar to that of the vast, essentially level, treeless zones of the Arctic. Scrub-forest Roughly between 1,800 and 2,000 meters, the dominant vegetation is scrub-forest. Trees here are stunted; except in sheltered spots they are more or less prone rather than upright. Net growth is slow, not only because of the short growing season but also because of the pruning effect of icy mountain winds. Very few tree species can survive in this harsh habitat. Coniferous forest In the forest community below 1,800 meters, Douglas fir, lodgepole pine, and western larch predominate. In the valleys, Engelmann spruce and subalpine fir are found. The somewhat lower and much better watered western valleys of the park support western redcedar and western hemlock. See page 54 Prairie At the eastern edge of the park below 1,200 meters, the forest gives way to the prairie community, composed mostly of soft-stemmed plants adapted to the conditions of low precipitation that prevail here in the rainshadow of the mountain range. Clumps of aspen, found in the prairie in sheltered spots, occur here in the transition zone between prairie and forest. The Forest Community A forest is organized vertically like an apartment house or office building, with layers corresponding to stories. The canopy is the branches and foliage of tall trees that form a roof over the community. Below the canopy are the understory trees: young individuals of the canopy species; and small, shade-tolerant trees that will never become part of the canopy. Beneath the understory branches is the shrub layer, occupied by knee-high-to-man-high woody plants; beneath that is the herb layer, where most of the ferns, wildflowers, grasses, and smaller woody plants grow. The forest floor is the zone of mosses, mushrooms, creeping plants, and forest litter (leaves, twigs, needles, feathers, bits of bark, animal droppings, etc.). The forest has a “basement,” too, interlaced by plant roots, mycelia of fungi, and tunnels of myriad animals. Each layer of the forest has its characteristic animal species, but most forage over more than one level. Some nest in one story and feed in another. The red squirrel races back and forth from the forest floor to the highest branches. The forest community also has a socio-economic organization. Every animal (and plant) takes up space and consumes a portion of the available nutrients. Each has a place in the community food chain—as, for example, herbivore, carnivore, or scavenger. Each directly or indirectly affects all the other organisms. The Forest Community The role of a species in the community, like the job and social function of a person, is its niche. Similar species of animals have different niches, thus lessening competition for food and living space. Thrushes hunt close to the ground; vireos and kinglets hunt among the branches; flycatchers snap up airborne insects. The flicker feeds upon insects, excavates nesting holes that are later occupied by other species such as squirrels and owls, and is preyed upon by the great horned owl; its niche is insect exterminator / food for carnivores / homebuilder. The great horned owl, hunting mammals, birds, and reptiles by night, preys on species different from those hunted by the goshawk, and thus occupies a parallel niche. When it dies, its remains, like those of other animals, are decomposed and return to the soil.
Sun, Green Plants, and Animals The sun is the source of energy for any plant-and-animal community. Green plants draw nitrogen and minerals from the soil, and in a process called photosynthesis use sunlight to convert raw materials (carbon dioxide and water) into carbohydrates (sugar, starch, cellulose), giving off oxygen as a by-product. Besides burning oxygen, animals depend on plants for food. Green Plants, trees and shrubs, grasses and sedges, wildflowers, ferns, mosses, algae and lichens—are fed upon by animals, which are unable to manufacture their own food. The Redback Vole, like other rodents, pikas and hares, seed-eating birds, grazing and browsing hoofed animals, and herbivorous insects, derives its energy from the seeds and other parts of green plants that it eats. The Garter Snake, feeding upon the vole, is dependent upon plants even though it does not eat them. The Great Horned Owl, preying upon the garter snake, is one more step removed from the green plants—but still dependent on them. Scavengers such as carrion beetles feed upon the carcass of the owl; the remains are then attacked by Decomposers, primarily bacteria, that break down the animal tissues into basic organic compounds. The Soil, enriched by the minerals and carbon and nitrogen compounds added to it by the decomposers (and by other processes such as fire) supports new green plant growth. Thus energy derived from the sun flows through the ecosystem in a food chain. A plant-and-animal community is a complex, interlocking web of such food chains.
A Pyramid of Numbers Necessarily, the number of plants in an ecosystem far exceeds the number of plant eaters, and the number of prey species must exceed the number of predators. During its lifetime, a golden eagle will consume a vast number of lesser animals. The combined mass of prey animals necessary to sustain an eagle greatly outweighs the eagle itself. Ecologists refer to this proportional relationship of mass between each link in the food chain as the pyramid of numbers. The diagram represents a numbers pyramid for the alpine zone. Because of its limiting environment, the alpine zone supports a lesser plant mass than the forest zone. As a result, the carrying capacity of the alpine is less than that of the forest. 1 Kilo Tertiary (third-order) consumers are the predators (Golden Eagle, Swainson’s Hawk, etc.) that feed upon other predators. Because of the 90% loss of energy at each level of the food chain, there will be very few hawks and eagles in comparison to the numbers of marmots. 10 Kilos Secondary consumers are the predators (weasels, shrews, carnivorous insects and birds, etc.) that eat herbivores. The animals at this level of the pyramid are often—though not always—larger than the animals they feed upon. But they are much less numerous, because it takes many prey animals to sustain one predator. 100 Kilos Primary consumers (plant eaters, or herbivores) convert plant tissue into animal flesh. In the process about 90% of the energy stored as plant food is lost, mostly as heat energy. In the alpine community the herbivores include pikas, marmots, ground squirrels, and ptarmigan, as well as herbivorous insects. 1,000 Kilos 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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 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.
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. The ForestOn Gunsight Pass, the rain lancing down, I found a sharpedged rock that split the continent in two. On both sides the rain rivulets ran down, a fraction of an inch determining the stream’s destination: Pacific or Atlantic. The Continental Divide is a mighty barrier, a line of consequence that does more than determine watersheds. Its effect in Glacier is dramatic, as a look at the forests will reveal. Obstructing the eastward flow of the moisture-laden Pacific winds, the Divide extracts a heavy annual tribute of precipitation from the air mass, forcing it to rise up the mountain chain, where it cools and condenses. Chief benefactors are the low western valleys, which respond with a lush growth of Pacific coastal-type forests. The eastern valleys, however, deprived of abundant annual moisture and exposed to the wind and temperature ravages of the prairie’s continental climate, support a dramatically different kind of forest. Here Engelmann spruce and subalpine fir are the climax trees, contrasted with such trees as the western redcedar and western hemlock of the mild and moist McDonald valley. Elevation exerts an additional restriction on the distribution of tree species. Since climatic conditions vary with change in elevation—lower temperatures resulting in shorter growing seasons, and increased wind exposure resulting in greater loss of moisture through evaporation—we would expect to find the forest composition change as we ascend a mountain slope. In Glacier, eastern valleys average 240 meters higher than western, and thus even if they had more moisture they would not sustain the redcedars and hemlocks. All plants have range limits, some narrow, some broad; and they excel where their particular set of preferences as to moisture, soil, sunlight, and wind exposure are best met. On sites that do not meet their optimum requirements, they face being crowded out by species better adapted to the prevailing conditions. Physical features of the land determine vegetation also. Certain trees prefer the moist areas along a streambed—the great black cottonwoods, for example. And on steep hillsides, avalanches prevent the growth of climax trees, permitting instead only shrubby, pliant growth—mountain-ash, mountain maple, alder, menziesia. Forest communities are named for their dominant tree species. Thus, an area in which Douglas-fir dominates is called a “Douglas-fir forest.” Glacier does have forests in which Douglas-fir is the climax species; these are chiefly dry areas, below 1,800 meters, with south and west exposures. But we usually associate the park with its Engelmann spruce-subalpine fir forests, found extensively between 1,200 and 2,100 meters, and with the western redcedar-western Because forests mature slowly and change is usually imperceptible, we are tempted to think of them as static and eternal. But since a forest is a community of living things, it responds to changes in the environment. Subtle physical or climatic changes, such as a rising or falling water table or a slight increase or decrease in annual precipitation, will favor some species of trees and hinder others, eventually altering the composition of the forest. Other changes are more dramatic. Most notable of these is fire. From Fire to ForestHeat lightning, glimmering soundless behind the western peaks. Then the first low rumble. At first the flashing had been from cloud to cloud, but now, as the storm nears, the first ground-spears appear, lighting up the night. Here is a big storm, many-celled, engulfing more and more territory beneath its angry bulk. Lightning dances into the dry August forest. In their towers the lookouts stay awake. Close strike and a flare-up! The ridge snag burns like a Roman candle, sending bright embers down. Valley, ridge, and peak blink on and off with blue light as the storm roars like night-firing artillery. Passing overhead, the low cloud belly brings a sudden lash of rain. But it is not enough: tomorrow will mean long hours of fire watch. The next day dawns clear, a morning of heavy dew. The ridge strikes did not ignite the forest. Inspecting the storm path, aircraft and lookouts find no evidence of fire. But two days later, in a morning of high wind, thin smoke plumes rise upward. Smoldering in the thick duff of the forest floor, a lingering hot spot explodes with the fanning wind. It quickly spreads from a hectare to ten while the quadrants are called in and the hot-shot crews dispatched; then to a hundred, bringing in the smoke jumpers and mobilizing the vast fire-control network. A thousand hectares, perhaps ten thousand might burn this week of big fires. In the resulting skeleton forest, the scene of devastation is almost overpowering: life seems forevermore excluded from this blackened ruin. But fire is nothing new to forest communities. We may think fire demonic because it takes from our life span this block of mature forest, a sight we will never again see in this place. But nature does not operate in terms of human time scales. This forest is simply pushed back closer to its starting point, to begin again its long progression toward a climax vegetation cover. Forest SuccessionThrough a series of complex vegetation stages, each characterized by different herbs, trees, and shrubs, the forest slowly returns The forest of Huckleberry Mountain on the Camas Creek road was consumed in the 1967 fire. By 1969, among the charred, lifeless trunks of the former forest, lush grass and sunloving fireweed, thistle, and paintbrush were growing. And by 1974 lodgepole pine seedlings along the road were a meter or two high. Lodgepole is a fast-growing tree that requires full sun to germinate. Forest fire is necessary for the regeneration of these trees: the intense heat causes the tightly closed cones to open, releasing the seeds that will establish the forest. So young pines developed among fireweed, spiraea, willow, and mountain maple shrubs. The lodgepole forest near the western entrance to the park has been developing since 1929, when fire destroyed the redcedar-hemlock forest in the area between Apgar and West Glacier. Beneath the scattered spires of old larch that survived the burn, the lodgepoles have now grown up, forming a canopy that shades the forest floor. Because lodgepole live only about 80 years and will not germinate in shade, this forest will not exist long. Shade-tolerant Douglas-fir, white pine, Engelmann spruce and western redcedar seedlings are now taking hold. But the physical characteristics of this area—the climate, terrain, and soil—are ultimately most favorable for western redcedar and hemlock; and unless other disruptions intervene, this area will eventually again become a dense redcedar-hemlock forest. But this will not happen quickly. The soil after hundreds of years of collecting debris will again become rich and moist. Young hemlocks will germinate on and near decaying logs. When old larches, firs, and pines fall, the slow-growing redcedars and hemlocks will take their places in the canopy. Forest succession is a more complicated story than this; it is a fascinating study involving herbs, shrubs, small and large trees, and animal populations. From location to location it will vary; only in its broad outlines is it predictable. It is based on the observation that, given time, a forest—or any other plant community—will progress until it reaches climax—that is, the stage that will perpetuate itself.
As the well-being of the deer herd depends on the predators that thin its numbers, so the long-term well-being of the forest depends on fire to rejuvenate it periodically. We must realize that wilderness is identified with fire, landslide, avalanche, windfall, and flood. Nature not only has learned to cope with these agents of change—she depends upon them for maintaining the delicate balances between landscape and life. There is in the business of nature, after all, more than the pleasing of man’s eye. Spruce MorningOf all times to get a rock in my boot! I had just started out, the morning was still cool in this eastern valley, and the heavy pack was not yet biting into my shoulders. Sitting down beside the trail, I leaned the pack against the base of an old spruce and began unlacing. I could hear the scratching of the red squirrel descending to investigate, but I didn’t look up until it let go with long indignant chatter at finding its territory invaded. I plunked out the pebble and began relacing my boot. Cautiously the squirrel came down, pausing frequently to scold, its lower jaw quivering with rage and exposing yellow rodent teeth. Neighboring squirrels joined in and soon the trees danced with flicking tails. Down the squirrel came, almost to the ground, then raced back up the tree, stopping at each lateral branch to deliver a vocal broadside. Finding no danger to themselves, the other squirrels soon quit the uproar and went about their morning business. I was beginning to suspect that I was committing some graver offense than the mere exercise of squatters’ rights—perhaps I threatened its cache of fir cones. Then into the corner of my vision shot another form, streaking soundless as a shadow; the squirrel also saw it—but too late. With a thin terrified squeak, the rodent started to go higher; but the pine marten was above it. The squirrel quickly reversed itself, sending bits of bark showering down. As the squirrel leaped from the tree in desperation, the marten overtook it in mid-air; they came down together. Clamping the limp creature firmly in its jaws, the marten strode up the incline of a fallen spruce. Before it hopped off onto a shelf of higher ground to disappear, it looked briefly back at me. I fancied I could read, fixed in its eyes, a certain recognition of my having distracted its prey. A breeze made me shiver, snapping me back from that swift vision of luxuriant fur, that blinding grace which flashed its orange throat-patch through the trees, and I realized I was sweating. For a moment I had been that squirrel, eyes wide with terror, seeing fate bear down, and powerless before the natural order of things. The incident got the other squirrels singing again; but the confidence was gone, and soon it was quiet. What dreams do squirrels dream, I wondered, looking around. I saw that place more clearly then, having been caught between a marten and its prey. I saw each spruce: its age, its condition, the onslaughts it had borne; the beargrass coming up in an opening; and down the trail a meadow that was yellow, white, and red with sulphur plant, mariposa, and Indian paintbrush. Bees, flies, spiders, and butterflies worked that little garden tucked among the crowding trees. Countless forms of life beneath the soil and bark, in tunnel, crevice, hole, and pocket, working unseen to sustain their lives, and somehow, when all were added up, maintaining the forest as well. A flicker called, its loud Klee-yer breaking the forest hush. Birds, mammals, plants, insects—all hide together here, their lives so skillfully embroidered that no loose thread exists that my mind might grasp to unravel and understand the work. The forest had once been a place that obstructed my view, a great blank to stride through, a few hours of necessary blur before the high lake or pass was reached. Now I was quite content to remain awhile beneath these great-boled trees.
Just above the forest floor is the herb layer, a seasonal layer of growth including flowers, mushrooms, grasses, and other small plants. Above that grows the shrub layer, then the understory of young trees awaiting their chance to take a place in the forest’s canopy high above. From the swaying canopy, exposed to the full force of sun and wind, to the dim, moist floor, the forest provides a wide range of habitat. Relatively few animals live in the treetops. The almost incessant motion makes nesting too hazardous for birds. Red squirrels venture up to cut cones in the canopy, but store their booty and make their nests farther down. In the mid-range between canopy and understory, goshawks and Cooper’s hawks nest. Woodpeckers, nuthatches, and sapsuckers forage on the tree trunks and nest in cavities they excavate or appropriate. Red squirrels and the nocturnal flying squirrels create a major traffic here, along with the martens and owls that hunt them. The understory and shrub layers house The most populated area, the forest floor, supports an astonishing abundance of organisms. Below the busy traffic of mice, shrews, and larger animals is a bewildering array of insects and other invertebrates. The attrition rate in the litter of the forest floor—a continual battleground difficult to comprehend—is enormous. The smaller the organism, the greater its numbers are likely to be. This humus-rich, moist soil teems with bacteria, and a handful will contain surprising numbers of small spiders, pseudo-scorpions and almost microscopic mites. Each year some two to three thousand kilograms, dry weight, of falling material litter an average hectare of forest. All this plant and animal waste—twigs, leaves, limbs, fallen trees, feathers, hair, feces, and carcasses—is processed by the armies of decomposers that thrive on the forest floor. With the aid of larger creatures that break up the plant and animal tissue, most microscopic bacteria are able to decompose from a hundred to a thousand times their own weight every day. Few trees die of old age in the forest. The seedling mortality rate is necessarily high, since far greater numbers of seeds germinate each year than can reach maturity. Of those that do, many fall victim to the ever-present dangers of disease, insect infestation, windfall, stream erosion, and fire. Insects alone present a formidable threat to trees, for they have evolved every means of attack—chewing and mining leaves, boring into twigs, eating cambium and heartwood, sucking sap, triggering galls. If the insect world did not police itself, aided by spiders, insectivorous birds and other animals, forests and other plantlife would quickly fade before the chewing, boring, sucking horde.
Some day soon, a sparrowhawk or weasel will interrupt the snake’s morning sun-bath. Until that time of sharp encounter, each has its own niche, a way of life, a shaft of sun, and food enough. A Walk in the Redcedar ForestClimax! The word takes on a true significance here, among these broad-based trees. When you enter this forest the road noise does not follow far—as, when you walk into a cave and turn a corner, sound and light are left behind. There is a surprising spaciousness, a feeling of openness in a mature western redcedar forest. With scant understory and the canopy so far above and everywhere complete, it seems like some vast, high-ceilinged catacomb, pillared by the huge, shaggy-barked cedars and the deeply scored trunks of the black cottonwoods. The floor is strewn with fallen giants in magnificent disarray, uplifted roots still grasping fractured rock. A rainy day is a good time to walk a cedar trail, when the dull light seems to shine from the wet moss, making the underleaves of devil’s-club and Rocky Mountain maple glow. Wind and rain, like light, penetrate with difficulty the latticework of this canopy; thin lines of fog develop over the bogs. The air is fresh with growing plants, snow-cold still when the first spring flowers appear. Fiddleheads of unfolding lady ferns line the trail in May, pushing up from the hub of last year’s leveled, lifeless fronds. Beds of trillium shine their white, three-pointed flowers like flashlights in the dark recesses. Unlike the small, hidden calypso orchid, which bears its purple spikes and yellow throat low above the moss, the trilliums make no secret of spring growth. They are bold, handsome plants, broad-leaved and tall, with waxy white petals that tinge to purple in their month-long bloom. Moss covers everything. Boulders are green and weightless-looking, resilient and topped with miniature forests of cedar seedlings. Ancient fallen trees are disguised with blankets of moss, sprouting hemlock here and there. The rich greens that characterize Glacier’s summers seem to begin here amid the moisture-glossed leaves of twinflower, bunchberry and bead-lily. Later, the spiders will spin thousands of kilometers of gossamer filament among the trees. The orb-weavers will hang their webs high and low, suspended in every opening. Walking through the forest then, you will see shafts of sunlight whirling in the higher webs until they seem like tops set spinning among the treetrunks. Indianpipes, the “ghost flowers” that need no light to grow, will break through the forest soil. Like mushrooms, with fruiting bodies that are nourished by underground Receiving an average of about 18 centimeters more annual precipitation than forests east of the Divide, Glacier’s redcedar-hemlock community hoards its moisture. Its dense growth and the surrounding mountain walls inhibit the circulation of drying winds. Mosses and ferns transpire their moisture, which you can feel; place your hand close, and you will sense a coolness like the air exuding from an ice cave. Draped from the tree limbs are long filaments of squawhair and goatsbeard, black and grey lichen strands that flourish in the damp air. Except for the black bear, few large animals inhabit the deep forest. Grizzlies find better forage in meadows or along the forest edge. Since shade discourages shrubby undergrowth, deer and wapiti will search elsewhere for browse. In summer, wapiti, grizzlies, and mule deer bucks tend to wander up into high meadows. Contrasted to the noisy, conspicuous birds of the prairie—meadowlarks and bobolinks—birds of the forest seem elusive and secretive. Although numerous, the varied thrushes, Townsend’s solitaires, and Swainson’s thrushes are seldom seen; but when approached, they fly silently off and are swallowed by the forest shadow. There seems to be serenity in a mature forest, as though the struggle for life is somehow suspended, the needs of the animals here less urgent, muffled. The towering redcedar forest seems to be no battlefield at all, but rather a monument to what Earth can do. The Perpendicular NightBehind Avalanche campground a trail leads back toward Lake McDonald Lodge. I decided to follow it one June evening, to experience the sensation of the deep forest changing into night. With the nearby mountain wall intercepting the sun, dusk comes early to this valley. On the prairie, night passes across the landscape in an even line, forthright as a waxing tide; you can almost feel the globe in its turning from the sun. There is reassurance in the night’s coming, its steady purple doming over the sky. But here darkness seems to sprout from the earth. It collects beneath the hemlock clumps, bridges the creekbottoms. It seems to flit from place to place. You look about, uneasy, trying to catch it here or there, but always miss its infiltrations. It captures the narrow clearings when you look away; pockets of tree-darkness join together, forcing the light upward until the tree-tops seem impossibly bright and distant. Through the trees I could see a dozen fires dance in the growing shadow, wood-smoke and camp sounds filling the air. Turning uptrail, I felt a reluctance to leave the presence of those fires—a senseless feeling, but strong. A growing forest-dread impelled me almost physically backward to those circles of firelight. I felt the need to be near a fire, to be reassured by heat and light. Fire was our greatest friend, our greatest weapon. With it we beat the long ages of ice and held the forest gloom away. There was no harm here, only silence; yet the longer I walked, with beard-moss hanging down like daggers all around, the more I craved the comradeship of fire. Continued on p. 104 The Vital Predator The merciless law of predation might at first thought seem cruel; but the predator plays a vital part in maintaining the balance of the biotic community. Without the controlling factor of predation, prey species quickly enlarge their populations. If plant eaters are not checked, the resulting excess population exceeds the carrying capacity of the range. Food supply rapidly diminishes. In a damaged range, competition and stress result, usually culminating in a massive die-off through starvation and disease. Ironically, predators thus provide a service to their prey. First to fall to the predator are the old, the diseased, the unwary, and the young. By removing many young and old deer from a typical herd, cougars lessen competition among the deer for choice range, thus tending to keep herbivore numbers at parity with the land’s carrying capacity. Only the strongest and wariest deer survive, ensuring that the fittest will continue the species. When man upsets this delicate balance—destroying predators in the hope of increasing numbers of game animals—the result is ecological disaster. In the 1930s, in a misguided attempt to “preserve” the whitetail deer herds of the park’s North Fork area, many coyotes and cougars were exterminated. In 1935 alone, 50 cougars were killed. Relieved of the pressure of predation, the deer flourished. In a few years, however, the normally adequate range was severely overbrowsed. Suffering also from this imbalance were wapiti (“elk”) and moose, ungulates that share the winter range with deer. Some predators are more specialized than others. The Canada lynx, for example, has oversize feet, an adaptation that helps it move across deep snow without breaking the surface. As a result, it is an efficient predator of the snowshoe hare, another large-footed animal. Relying on this adaptation, the lynx feeds almost exclusively on snowshoe hares. Consequently, its numbers inevitably fluctuate with the 10-year “boom and bust” cycle of the snowshoe. The coyote, on the other hand, is a generalized predator, exploiting whatever prey is currently abundant. Should mice or ground squirrels be in short supply, it will subsist on anything from grasshoppers to berries until favored prey again becomes available. (Animals that normally eat both plant and animal food are referred to as omnivores.) Generalized predators are thus better equipped to survive temporary ecological imbalances, maintaining their numbers at relatively consistent levels from year to year. Carnivores all, the animals on these pages illustrate various adaptations for capturing prey. The population of the Canada lynx, which is widely distributed in Glacier’s coniferous forests, fluctuates in cycles. The lynx is abundant or scarce depending on the population condition of its chief prey, the equally cyclic snowshoe hare. The cougar, which feeds primarily on deer, requires a large territory. Because of its strength, stealth, and speed, American folklore has given this wary cat a false reputation as a man-stalker. The red fox depends largely on a well-developed sense of smell to locate its prey; it also relies on its keen eyesight, speed, and agility to capture mice, hares, birds, and whatever else it can run down or surprise. To feed its demanding young, the Swainson’s thrush hunts for insects along the forest floor and in the dense underbrush. This thrush relies on its secretive behavior to protect its nest near the ground from detection by other predators. Armed with enlarged forelegs, the crab spider waits on or near flowers to ambush visiting bees, flies, or other insects. Its venom produces a quick kill, allowing it to attack insects many times its own size. The spotted frog is a large-mouthed predator that not only eats water striders and other insects but also gulps down smaller frogs and small fish. Protective Coloration To escape extermination, each species must in some manner foil its enemies. Protective coloration is one of the more common adaptations helping to do this. Most animals resemble their environment to some extent. The conspicuous markings of some, like the bitter-tasting monarch butterfly or the striped skunk, seem to function as a warning to prospective predators that it is in their best interest to look elsewhere for a meal. Some animals, such as the white-tailed ptarmigan and the snowshoe hare, have seasonal changes in plumage or pelage, wearing white in winter and brown in summer. Even predators, such as longtail and shorttail weasels, benefit from seasonal camouflage. Protective coloration makes them less noticeable to prey species and to larger predators. Many insects, too, change coloration with the season. Bright green grasshoppers of early summer become more brown with each molt, matching the changes in the surrounding vegetation. Obliterative shading is especially important to animals that frequent more than one habitat. Seen from above, turtles match their dark background; from below, because of their lighter underbody shading they blend into the bright skylight. Disruptive coloration aids in breaking up an animal’s outline. Butterflies and moths commonly have disruptive wing markings. The distinctive shapes of eyes can be concealed. Eye coloration may mimic body color—as in the green katydid—or the eye may continue disruptive body markings. Ground-nesting birds are especially vulnerable to attack. Their eggs tend to be heavily blotched with earthy colors, making them less conspicuous. Chicks also carry these disruptive colorations on natal down. Most mammals, with coats of brown or gray, are inconspicuous when motionless. Deer fawns are endowed with speckled coats, mimicking the sun-flecked forest floor; this disruptive coloration, coupled with absence of scent and their instinctive “freezing” behavior, makes it difficult for predators to detect them. The whitetail deer not only uses its white “flag” to warn others in the herd of danger; it also allows a pursuing predator to use it as a target. When the tail is suddenly dropped—abruptly obliterating the bright white patch—the deer seems to disappear into its dim surroundings. Since overly conspicuous animals are prone to predation, natural selection favors development of appropriate camouflage. For such ground-dwelling birds as the white-tailed ptarmigan, camouflage is an important survival adaptation. The ptarmigan changes its plumage to match its surroundings: it is white in winter, speckled in summer. Moving slowly and refraining from flight, it is less likely than more-active birds to be detected by sharp-eyed, motion-conscious predators. Birds that when hatched are covered with down and are able to move about freely are called precocial. They are less dependent upon their parents than are altricial young, which are naked and helpless when they hatch; but they must rely heavily on a resemblance to their surroundings for survival during their first flightless weeks. This spruce grouse chick, which blends into its sunflecked forest-floor habitat, is an example of a precocial bird. The bold disruptive pattern of the killdeer chick’s plumage helps this precocial bird avoid detection in its open-prairie environment. This adaptation, coupled with the chick’s instinct to freeze at the approach of danger, ensures that enough young will survive to perpetuate the species. Ursus arctos horribilus: The Vulnerable King At the apex of the food pyramid, this great beast is unquestionably the king of Glacier’s biotic community. Yet the long-range future of the grizzly bear is uncertain. With the grizzly exterminated from most of its former range—which once extended into the midcontinent and south into Mexico—its numbers have dwindled in proportion to its diminished range. Present concentrations in the contiguous United States remain in and around Yellowstone and Glacier National Parks. Probably fewer than 200 of these magnificent creatures live in Glacier National Park. Grizzlies are easily distinguished from the more common black bear. In addition to larger size and heavier build, grizzlies have a characteristic shoulder hump; long, conspicuous claws; and a broad, concave face that gives them a “dished-in” appearance. Fur is usually brown; like the fur of the black bear, however, color may range from black to yellowish. Light tipped hairs make the fur appear frosted, giving rise to the nickname, “silvertip.” Grizzlies, popularly considered arch predators, are more accurately described as omnivores. Carrion, grasses, cow parsnip, and several species of berries, bulbs, and tubers make up a grizzly’s diet, along with insects, small mammals, and an occasional ungulate that it can catch. As a result, grizzlies play several roles in the biotic community, functioning as herbivore, scavenger, and predator. Ranging widely in all life zones, grizzlies follow the spring snowmelt up to the alpine meadows, returning to lower elevations to hibernate from November until April. One to three cubs are born in midwinter during hibernation. Since the maternal bond lasts two years, a sow will accept a mate only every other year. Mortality of subadults is high, resulting principally from competition among the bears themselves. As with most animals, range—habitat—appears to be the limiting factor of grizzly populations. The grizzly is normally shy and fearful of man—but highly unpredictable. Wounded or sick bears, sows defending cubs, young adults, and bears that have become conditioned to human scent are the most dangerous. As humans continue to encroach on grizzly territory, odds of confrontation also increase. Recent fatalities and personal injuries inflicted by grizzlies pose a vexing problem to the National Park Service, which is charged with visitor safety on the one hand and protection of the park’s remaining grizzly population on the other. Continuing study of grizzly ecology and increasingly enlightened bear management programs will, it is hoped, allow man and bear to co-exist in a wilderness both require. Grizzlies are fond of succulent spring grasses. Traversing all life zones in the park, the grizzly is a true opportunist, eating anything from ants and berries to wapiti. Seldom will a grizzly exceed 225 kilograms in Glacier. This is a young adult. In 1916 the kokanee salmon, a small, land-locked form of the Pacific coast species, was planted in the Flathead drainage. With the first planting augmented by additional stockings, the fish thrived in cold, deep Flathead Lake, and, to a lesser extent, in Lake McDonald. The salmon fed almost exclusively on zooplankton. By the mid-1930s, salmon runs were becoming established. The outlet of Lake McDonald provides an ideal spawning site for the salmon. The fast-flowing water is clear, cold, and shallow, and the creek bed is gravelly. Averaging 0.3 meters in length and weighing less than a half-kilo, the 4-year-old adult salmon cease feeding and begin to migrate. Many thousands swim the 100 kilometers from Flathead Lake to McDonald Creek. Males appear in the creek first, arriving in late September, and are soon followed by the females. Using her tail to dig a redd (a shallow nest depression), the female deposits about 650 eggs. After fertilization by the male, the eggs are covered over. The adults die within three weeks after spawning, their bodies exhausted from the rigorous migration journey and the weeks-long lack of sustenance. Egg fatalities are high, due to stream erosion and disturbance by other spawning salmon. Hatching in late March, the fry work their way out of the gravel and migrate downstream. Attracted to the 75,000-150,000 salmon concentrated in a 3-kilometer stretch of shallow water, bald eagles begin gathering at McDonald Creek in October. It is not known where the eagles come from or where they go after the spawning run. Glacier has fewer than 20 summer-resident bald eagles, and these are distributed among the remote lakes of the North Fork area. In 1939, 37 bald eagles were counted along the creek. By 1969, 373 were reported, representing approximately 10 percent of that year’s estimated winter population for the contiguous United States. Since 1960, the count has averaged 240 birds. (In 1977 there were 444.) Eagles feed by swooping down to pluck salmon from the water or by wading out to grab a fish stranded on a shallow riffle. An eagle may consume as many as six fish a day. Immature birds are not as adept at catching fish and may harry adults or other immatures into releasing their catch. From its vantage point, this mature bald eagle examines the waters of McDonald Creek. Average weight is 5.7 kilograms; average wingspan is 2.2 meters. Females are slightly larger than males. This immature bald eagle lacks the familiar white head and tail of the adult birds. It will not acquire those markings until it is several years old. Breeding male and female kokanee salmon are easily distinguishable; as spawning time approaches, they change appearance. The dark gray backs turn red; heads become green, and the males develop humped backs and hooked jaws. Swooping upward with a fish, a mature eagle heads for a convenient perch to consume its catch. A strategically located tree may contain 30 birds. Grassland, meadow, tundra, or any other area in Glacier suitable for plant growth and supplied with abundant sunlight produces an extravagance of wildflowers. This display of various shapes and colors is neither an accident nor a mere decoration of nature. Nor would Earth’s recent explosion of mammal and bird species have been possible without the evolution of flowering plants. Two hundred million years ago, early in the Age of Reptiles, angiosperms (flowering plants) had not yet evolved. Plant reproduction still relied on spores and cones. Then, during the Cretaceous Period, the last sediments were being laid down in the inland sea that covered most of Montana. (It was these sediments that the ancient Precambrian rocks of Glacier’s mountains later overrode, forming the Lewis Overthrust.) During this period the evolutionary miracle occurred: flowering plants—grasses, vines, shrubs, broadleaf trees, wildflowers—inherited the Earth. The timing was important. As Earth’s tropical climate gradually changed to temperate extremes during this period, the domination of cold-blooded dinosaurs ended and the moisture-demanding coniferous forests that had covered the earth in green monotony began to shrink. Angiosperms provided a solution to the ecological void: grasses and forbs grew where trees no longer could. Most important, relationships evolved between this new class of plants and the relatively few species of insects then existing. Insects began to use the pollen of flowering plants; the angiosperms, in turn, evolved bright petals and nectar that exploited visiting insects for the plants’ own reproductive purposes. This partnership allowed insects to diversify rapidly, evolving new, specialized forms such as bees, moths, and butterflies. As a result, predatory forms of insects and arachnids also rapidly diversified. The most dramatic change, however, involved warm-blooded birds and mammals, whose high rates of metabolism required high-energy fuels. Unlike gymnosperm seeds, which contain no protective covering, angiosperm seeds are surrounded by a fruit. The development of these highly nutritious seeds, and the attendant explosion of insect species, ensured survival of the newly evolved birds. As birds diversified into seed-eaters, insectivores, and carnivores, mammals, then uncertain little ratlike creatures darting among the feet of dinosaurs, began a rapid rise to dominance; grasslands promoted an explosion of herbivorous and carnivorous species. The evolution of angiosperms, and the animal revolution it made possible, came with amazing speed. Most significant, it was a vital first step upon which the meteoric rise of man depended. Indian paintbrush is common at all elevations below tundra. It may be white, yellow, orange, pink or red. The actual flowers, inconspicuous and green, are surrounded by brilliantly colored bracts. Semi-parasitic on other plants, paintbrush is normally found growing in conjunction with other wildflowers; its roots steal sustenance from neighboring plants. Yellow stonecrop, widely distributed in forest and scrub-forest zones, is one of the park’s few plants having succulent leaves, an adaptation that helps it survive in such situations as dry, rocky outcrops. The Calypso orchid grows in the cool, shadowed forest where light is dim. It lives in partnership with certain fungi that exist about the orchid’s roots and seem to help nourish it. Silky lupine, a legume, has nitrogen-fixing nodules on its roots, thus allowing it to grow in nitrogen-poor soil. It is widely distributed in grassland and forest communities. Most of Glacier’s fires are lightning-caused. Strikes may flare up immediately; or fires may smolder in the forest duff for days until fanned into flame by wind. Ground fires may race through the forest understory, causing minor damage; or they may bridge the understory and reach the canopy, thus becoming rapidly spreading crown fires. Under certain conditions, uncontrollable infernos may develop, generating terrific winds and heat. These rare conflagrations are called fire storms. Every type of forest habitat has climax vegetation—trees and shrubs that are best suited to the site and thus maintain themselves indefinitely if not disrupted. After a major fire, habitat conditions are usually so altered that the site must pass through several seral stages before conditions are such that climax vegetation can return. A sere is a series of plant communities that follow one another in orderly fashion until climax conditions are again reached. Lightning fires occur most often during the hot, dry weeks of late summer. When the forest is dry, lightning often causes quick flare-ups. The forest may continue to burn for days after the main conflagration has passed. After a major fire, sun-loving grasses, shrubs, and wildflowers quickly invade the former forest. Deer and wapiti benefit from these new food sources. Lodgepole pine, a pioneer species quick to take over burned areas at lower elevations, grows rapidly. These trees are five years old. This is a Glacier National Park forest 80 years after a major fire. Sudden hammering made me jump. Above the forest darkness, a pileated woodpecker leaned out from a high larch snag, braced against the trunk by its specialized, stiff tail feathers. This was the first time I had seen this big white-and-black bird, the “cock-of-the-woods.” There was ample evidence of his work: the deep, oblong excavations in the trunk and the pile of large wood chips at its base, both characteristic of this species. Again he hammered, and I could see the chips falling. After a little edge-work around the hole, he extracted a grub and flew off, yammering against the advancing dark. Near a stream I stopped to sit down, to listen to the water and maybe catch sight of some small animal. Across the narrow defile, from a slope dense with young hemlock, came the buzzing note of a varied thrush. Several notes followed, all on a different pitch, all drawn out, level and clear; the quality was pure but songless, disjointed, deliberate, like someone testing the reed of a strange woodwind. There seemed no gladness in the heart of this thrush. The song was dark, haunting, lonely. On the trail ahead I could make out a bird hopping rapidly along. After passing the spot I could hear its song. There couldn’t be a hundred meters between us, yet it seemed to be coming from a great distance. I listened for as long as it would sing. I tried to hear it for what it was, a male Swainson’s thrush proclaiming its territory. But the ethereal, flute-like phrases seemed an evensong made not for man’s ears but only for the forest itself. I hurried on after the bird had ceased. It was getting dark beneath the trees, but I was beginning to be aware of creatures underfoot, the mad dartings of shrew and vole, more imagined than seen. When a deer mouse jumped away I got out my flashlight. Soon the beam caught a woodrat sitting atop a fallen log. The light didn’t bother him in the least; as I approached, he picked up his bushy tail in his forepaws. Whiskers twitching, he looked more caricature than real. Then he bounded off the log with graceful, arching hops, and disappeared into the night. Against a patch of sky that appeared in a clearing, I could make out bats, circling and dipping like swallows. Locating a hovering moth, I kept the light beam on it until it vanished into a furry streak of silence. It was time to head back. By now it had become utterly dark within the trees, a moonless, sightless, alien The flashlight beam probed ahead along the trail. The exposed roots were given unnatural shading and they seemed to thicken and squirm as I approached. On either side the tree trunks appeared to step backward from the dim glow of the light. I felt lost in this night, thinking of the great darkness in all the timbered ridges that ran westward from the Divide. In this vast cathedral of crowded tree and peak, night was stood on end, the stars shrunken to a circle overhead, as if seen from the bottom of a well. Mouselike, shivering, insignificant in this wilderness, I scurried back to find a fire and fill my empty senses with its heat and snap and light, holding off the fright of night and thinking of tomorrow’s sun. Scrub-ForestThe crowning beauty of Glacier—the high, cirqueheld meadows that scent the wind with wildflower and waterfall—belongs to the zone of scrub-forest. At Logan Pass you are introduced to the highlands. Here an exquisite upland basin holds the Hanging Gardens, a wildflower-clothed gradient laced with stair-step bogs and lines of wind-bent subalpine fir. In the dawn sun, before the first engine noise, it shines unbroken, dewbright and sagging like a spider web secured to the circle of surrounding peaks. This is the region the hiker remembers best. The tall mountains wear this zone close to the cliffs, and the trails encounter it near the passes or follow it for long, level stretches, as along the Garden Wall. I remember Preston Park and Fifty Mountain, the fire-touched bench of Granite Park and the first sight of Sperry chalet, built on a brow of rock at the upper reach of trees. But most of all I remember the terrible waterfall that becomes Bowman Creek, the plunge of nearly a kilometer that drains the magnificent upland bench called Hole-in-the-Wall. Hole-in-the-WallSeptember. The season is growing late, the meadow-rue dying and the leaves of the wild strawberry failing at last. Everywhere the red contagion of autumn surrounds the It has been eight years since I last visited Hole-in-the-Wall, but I retain its dimensions and hear its dozen waterfalls at will. Once you have seen this basin you have a measure by which to judge the high country and a thirst for the meadows at tree-line. In Glacier, treelimit ranges between 1,850 and 2,300 meters, depending on local conditions. The upper limit of tree growth—rarely an even, horizontal line—is generally an indistinct band running erratically across a mountain’s face: a tension zone reflecting variations in wind and sun exposure, degree of slope, snowpack accumulations, and the presence of adequate soil and water. Subalpine fir, whitebark pine, and Engelmann spruce do not relinquish easily their upward climb; where conditions become severe, their growth is retarded and their stature dwarfed. Deformed and pruned by wind, their leaders winter-killed when they outreach the protection of the winter snowpack, trees become shrubs, forced to hug the ground. Size belies age in these elfin forests, or krummholz, where the growing season is painfully brief and progress is always uncertain. A twisted, gnarled little bush, more snag than live branch, bearing a single cone or two, may be senior by a century to the giants of its race in the valley below, which yearly shower the ground with an abundant crop of cones. This time I will come from Goathaunt, passing Lakes Janet and Francis, reaching Brown Pass from the east, and camp in the spectacular garden between Brown and Boulder Passes. Meadows and rock slides break the forest as the trail gains elevation and distance through the valley. The spruce and fir thin out rapidly at the valley head, the trail climbing the grassy slope to low, broad Brown Pass. Below the pass is Thunderbird Pond, which receives the meltwater from a glacier high on a shelf of Thunderbird Mountain and is bordered by a low jungle of willow. In the water stands a bull moose, its heavy, fully formed antlers ready for the season’s impending business. I was hoping again to see Cassin’s finches and Audubon’s warblers on the pass; but the fir grove is quiet. Sitting down to rest and listen, I become aware of a strange silence. No birds sing or flit among the trees, no alarms pass back and forth among alert ground squirrels. There is no wind—an odd condition for the Continental Divide. This place seems to be holding its breath. High overhead, a veil of cirrus cloud arranges long spears across the sky. Moving off the pass, along the dome of Mt. Chapman, I experience anew the old excitement of this high country. Abruptly the gorge of Bowman valley opens up, revealing It is not the climb that makes your heart pound now; the trail is suddenly narrow and cliff-defiant, cut by the plunging waters of snowbanks far above. These are splendid peaks, unmatched in a land of muscled, brutal earth. Even the air seems to retain the scent of glacier work. At last the view of Hole-in-the-Wall, a staircase cirque excavated between the gigantic spread ribs of Mt. Custer. The slopes of beargrass are seed-spotted and gaunt now, the white fullness gone. Western pasqueflowers have accomplished their magic transformation; known in this season as old man’s beard, they nod their tufts of grizzled seedhead silk in the wind. Red and yellow monkeyflowers bloom yet, crowding along the many stream courses, and waterloving sedges and mosses surround pools of collected water on the broad horseshoe tiers. A spur trail drops down into the campground on the last ledge. Through a cleft in its lip plummets the gathered water of the basin. From the valley below, the waterfall appears to be springing from a hole in the headwall, giving this basin its name. Down, down, down, roars the water where once a mighty glacier ground its teeth. I leave until later the making of camp; by now the sharp shadows of Boulder Peak stab the valley forest and are beginning the upward assault of Thunderbird. Around the basin headwalls, last winter’s snowbanks remain formidable. Snow caves send out meltwater torrents. Glacier lilies and patches of spring beauty line their fringes. Pasqueflowers bloom in pockets. Here, among the asters of August, bloom also the first flowers of spring, shooting up as the snowbanks shrink, making these spots of snow-free ground a patchwork of May and July, August and June. The shrubs that line the furious water are willows, still bud-swollen this tenth day of September. The coming days will bring a sharp surprise. Winter will soon stop the melting of this snow. Could it be that I am seeing the first year of a reawakening ice age? If so, each year the snowfields would grow thicker and broader, connecting the shelves into one ice mass again, lilies and willows entombed, the summer heat failing to rescue them, until the ice at last began to slide, stripping the soil and once more plucking at living rock. Then these dwarfed fir, which cling precariously to the cliffs and hide behind the backs of boulders, would be in more danger than they were from their recent antagonists. Engulfed by ice, they would know the shearing wind no more. Their skeletons would rain down into the valley below, signalling another long forest retreat. But they have waited out the mountain ice before and would send their seeds again to this valley, Evening brings out two sleek mule deer does. As they graze, their large ears stand erect, sorting out the lesser sounds from the ceaseless roar of water. Both raise their heads and point their ears, statue straight, at the scuttle of a porcupine. A noise among the rocks draws a backward glance and focus of those ears. I would like the sensitivity of such fine equipment, to hear what deer have always heard. Setting about the business of camp, I wonder about those animals that watched me for a while, then moved off, having seen a tent go up before. With the appearance of the moon the wind increases and they test the air more often now. Do they have visions of cougar or grizzly with every snap the wind delivers? In summer these high meadows see a surprising variety of animal life. Briefly out of hibernation are marmots and the handsome golden-mantled ground squirrels. Mice, voles, shrews, and woodrats run among the shadows, feeding on the season’s feast of seeds and insects. A nightmare for these are the fierce little weasels that haunt the rocks. Tracks of cougar and wolverine are sometimes seen, often teasingly fresh; to glimpse either of these elusive predators is to taste the finest wine of wilderness. Before the berry season, grizzlies grub the meadows for the tasty bulbs of glacier lilies and the tubers of spring beauty; often distracted by the scent of a ground squirrel in its burrow, they sometimes make a huge excavation for a small reward. White-crowned sparrows sing in July from the low tops of the battered trees, though their nests are on the ground below. Grey-crowned rosy finches patrol the drier ground for seeds while water pipits hunt insects in the wet areas. High above, a golden eagle scans the basin again, circling slowly before following a ridge south to sight another likely slope in its 10,000-hectare territory. The moon shines through the tent top. The wind, blowing more violently now, shivers the nylon and interrupts the voice of the waterfall. I have followed the pasqueflower run from the April prairies here to its highest bloom near treeline. I think about the triangular seed pods of the glacier lilies, colonies of steep-throated blue gentians, and the season’s last glory of goldenrod. Indian paintbrush, from white to fire red, blazes the slopes that light the fringes of sleep. I awake to a determined rain, the moon gone and the tent shuddering with wind-blast. I try not to think of the steel-cold air, and slip into a fitful sleep that seems an endless treadmill of rocky trail. Stiff and unrefreshed, I look out into the dawnless morning. The tip of Thunderbird is detached from its base by grey clouds swirling at its throat. A wave of sleet slants down, dancing on the rocks, chanting triumph So I must make my escape, short of Boulder Pass. Unattainable now, invisible above the cirque, that high pass grows in my memory. This testament to what a glacier can do, to the struggle of trees and the life-pioneers that invade such harsh places, is at my feet but shrouded with snow. My hands grow stiff and numb in the blunt work of packing up. I had wished to see Kinnerly Peak again, rising from the western Kintla valley, and walk along black ledges of the lava that floors the pass. Beyond it grows a grove of subalpine larch, stately, seldom encountered, the least common tree species in Glacier. Confined to this narrow zone between forest and alpine, it reaches up tall and proud, impervious to the gruelling climate that makes cowering shrubs of other trees. But all must wait another year, for this season comes down hard. And the will of winter is to erase whatever summer had devised. TundraPorcelain-cold, the November sun dawns in the southeast sky. The ledges, ice-encrusted, layered with sleet from a recent squall, whistle the cold morning wind aside. Rattling down, a slide of rock plunges off the final ledge, seconds passing before the hollow sounds of impact clatter back. Like an apparition of winter itself, white beard bent sideways by the wind, a mountain goat steps to the precipice edge. Looking out across the vast white void, its long belly hair and pantaloons streaming with the ceaseless wind, this strange animal, product of some unfathomable ingenuity, hesitates but a moment; dropping down from step to invisible step along the sheer rock face, fracturing the ice glaze as it goes, it turns a wall and disappears. A nimble, eight-months-old kid follows. Blinking and twisting in the dull light, the shower of shattered ice clinks softly downward against rock, fading away like the short summers of this place. But while the wind chants winter, life has made a passage here, and also waits, hidden in seed and root and den.
Far below the pass that connects Mount Now they crouch behind the wind-deflecting rocks, dozing in the meager warmth of the morning sun. Near the snowless summit crags, a flash of brown fur zigzags among the rocks. That would be a pika. Only for a moment does it show itself, so quickly does it move. Also called the rock rabbit, the diminutive pika belongs to the order of hares and rabbits. Resembling a small guinea pig, this sturdy creature spurns hibernation as a way to beat the challenge of winter. Instead, it spends the summer laying in a store of hay for the lean season, spreading cut grass to cure upon the rocks and tending its “haystacks,” on which its survival hangs. Winter is a great peril to small mammals. Their small bodies, because of a large surface area in relation to volume, retain heat poorly, and their high metabolic fires consume calories quickly. Great amounts of energy are required to sustain an active animal in rough terrain, placing further demands on the animal’s capacity to survive the cold. The pika may need to stack as much as 25 kilos of hay; to keep its furnace burning during winter it will have to fuel its stomach almost hourly. Small animals of cold climates often show distinctive body adaptations. On the pika the small, rounded ears lie flat along the head, the tail is inconspicuous, the legs are short; heat loss from exposed surfaces is thus reduced. Fur insulates the soles of the pika’s feet while at the same time providing good traction on steep rock faces. Hidden below these rocks are the hibernating marmots and the sleeping ground squirrels. Beneath the snow the mice, shrews, and pocket gophers struggle on with their lives. But above ground, directly confronting this arctic climate, are the pika, the ptarmigan, and the mountain goat. A triumph of adaptation, the mountain goat faces the winter day without benefit of either the pika’s den or the ptarmigan’s snow roost. The nanny and kid descend from their Not really goats at all, these relatives of the European mountaineering chamois are insulated from the wind by coats of long, hollow-haired fur overlying woolly underfur. They are stocky, stiff-legged, and deliberate, able to negotiate the walls and pinnacles with their superbly adapted hoofs. The unique design of these hoofs gives the animal great traction and stability on precarious crags. Opening towards the front, the cleft between the two hoofs spreads each outward as the animal descends a slope, helping to grip the rocky surface. In addition, the large, rough, and pliant sole of each foot conforms to the bare rock, increasing traction. There is little need for the goat to leave its steep sanctuaries; it can subsist on lichens and mosses if browse is not available. It depends on the inaccessibility of the cliffs for its security. Accidents, avalanches, and rockfall are greater enemies than predators. Golden eagles sometimes attempt to knock newborn kids from ledges and a young goat quickly retreats under its nanny when an eagle soars by. With the protection of sharp spike horns and a terrifying terrain, adult goats seldom fall victim to cougar or grizzly. It will be a long time before the snow releases this land and wapiti, bighorn, grizzly, and cougar wander back into these high basins. In this winter minimum of life, the spring songs of rosy finches, water pipits and white-crowned sparrows seem an impossible extravagance.
Yet once exposed, you acquire a craving for the look of tundra. Nowhere else is there such an impatience for spring—the flowers rush into bloom; the male water pipit soars, its skylark song crystal sharp in the thin air. The nesting birds are restless, for sun-days and warm days are few, precious, and quickly spent. Insects and spiders abound—flying about the peaks or crawling Summer brings bands of bighorn rams up from the valley to explore the highest meadows. Though not so sure-footed as the goats, they too have hoofs adapted to climbing steep faces, and they walk the slopes not far below the goats. Marmots, which whistle sharply when threatened, spend their days sunbathing and grazing; they must fill out their now loose-hanging fur coats with life-sustaining fat for the coming winter. Alpine animals are blessed with mobility and can choose their weathers, retreating to burrow, den, or rock-harbor to escape the worst fury of storms. But what about the plants, rooted forever in one spot, assaulted by an untempered sun and a drying wind, and facing the almost daily threat of freeze and storm? Alpine plants, through their design and growing habits, have adapted themselves to the rigorous demands of this climate in many ways. Most plants are perennial: there just aren’t enough days or nutrients available for the growing of entire plants each year from seed. And they have the ability to grow and carry on photosynthesis at temperatures just above freezing, thus extending their season. In this zone, temperatures are rarely above 15° C; the mean summer temperature is about 10° C. But a flower such as the alpine buttercup, which is found at treeline or above, can grow through several centimeters of snow; heat given off during the plant’s respiration will create an opening through which it can emerge. Plants have various adaptations to meet the demands of the alpine environment. Yellow stonecrop, not restricted to this zone, is nevertheless able to survive here because of its fleshy succulence and a waxy covering that prevents water loss. On some plants, protective hairs covering leaves and stems help retard the burning effects of wind and sun. Often this pubescent foliage looks more grey than green, for the soft hairs mute the color. Cushion growth is another alpine adaptation. The moss campion cushion, covered with delicate pink flowers, grows to about one-third of a meter across and only 3 to 5 centimeters high. Spreading out close to the ground, the plant avoids the major violence of the wind and hoards moisture like a sponge. The dryad, growing abundantly on the windy sweep of Siyeh Pass, shows alpine adaptations in several ways. The energy of the mature plant is channeled primarily into reproduction: its large flower, supported by a short stem, matures quickly; and it produces many seeds, ensuring germination of a few. An evergreen, it begins to synthesize water and carbon dioxide into food as soon as the snow is gone; and its rolled leaves prevent rapid evaporation. It grows as a low and woody mat that year by year extends itself through the production of new shoots that carpet the rock. Mat growth has the advantage Compared to the forest, the heartbeat of the tundra is painfully slow. Here a plant may grow for a quarter of a century before it has acquired the reserves necessary for flowering. Contrasted with the progress on the tundra, forest succession races by with dizzying speed. Yet imperceptible as the change may be the alpine plant community also passes from pioneer to climax. Beyond the limit of other plants, lichens thrive, encrusting rocks with their rainbow colors. A lichen is actually a primitive and highly successful association between a fungus and an alga, working together for mutual benefit. The fungus protects the delicate alga, trapping and holding moisture; the green alga, in turn, produces enough food to sustain the needs of the fungus. Generating rock-disintegrating acids that help secure this partnership to the rock, lichens, along with physical weathering, help break down the rocks into soil particles. Collected in pockets by run-off or wind, rudimentary soil is slowly invaded by cushion plants. After centuries of colonization by these, while the meager soil is deepened and enriched and moisture retention is increased, other plants move in, climaxing at last in hardy grasses and sedges. As in the forest, pioneer species change the environment to their detriment, creating a habitat better suited to other species. Although it will progress with geologic slowness, the rocky ground of Siyeh Pass—its plant cover presently scant and wind-rowed by frost-heave and relentless wind—will in time develop grasses and sedges, the climax vegetation of the alpine meadows.
There is a penalty to simplicity. In the lowland, the long food chains and diversity of species, the long growing season, and the abundant food supply give the forest an adjustment mechanism and healing power not found on the critically balanced tundra. The greater the variety in a plant and animal community, the greater the stability. So in the alpine world there exists a paradox: the most durable life forms constitute the most fragile community. The Water CommunitiesSnowfields begin again their summer-long melt. The alpine stream, vocal again, collects its water from a thousand places. Miniature gorges drain the meadow, gurgling with the sparkle and rush of meltwater in the lengthening spring days. Gathering volume, the stream seems to hurry faster; at the first rock staircase, it begins to sing. I follow the gully downward, drawn like the water. There is excitement in the growing dash and roar, a wind-gust sweeping spray into the air. A rainbow appears, holding steady to the swirling cloud of spray, then doubles and abruptly disappears. At the first great plunge the water lunges outward over the lip. Like glass at shattering, long shards lance out. But the wind feathers the sharp edges as they fall. The close thunder of a waterfall beats at your head, and your mind must shout to think. Here is water, a most amazing and most important substance. Perhaps some of this same water was once part of the ancient sea in which was laid down the mudstone of this ledge; was once drunk by dinosaurs; has coursed the globe countless times; and has flowed in this very stream before. In solid, liquid, or gaseous form, it goes through its own cycle. Together with sunlight, water makes possible and maintains all life on Earth. Ouzel MusicA glacier might cling to a winter snow a hundred years and turn it to ice, a blue tool to rasp and pluck at rocks, before letting it go. Lingering summer snowfields might delay its passage for a time. But the water always wins at last, becoming, in one decisive instant, liquid again, and beginning its long journey to the sea. Plants and dry air will intercept some of its molecules, sending them back into the atmosphere to bloom as fog and cloud; but as rain, snow, or dew, these are soon commissioned to the land again. Water is so familiar to us that we seldom think about it. We know that fish swim in the lower lakes, and we are vaguely aware of the bewildering assortment of life-forms abounding in a pond. But life begins in the streams. Even cups of cold meltwaters, scooped out of a rivulet only a few meters away from its snowbank source, contain some life. Snow algae, which grow on the snowbank surface, often sufficiently dense to give the snow a distinctive red complexion, are released into the meltwater. In summer, small invertebrate life can be discovered in the standing pools of even the highest cirque. But conditions are not good for the development of complete aquatic food chains in the streams and lakes of higher elevations. Alpine lakes, or tarns, support little visible life. Often flanked by high ridges and peaks, many tarns receive scant Moving out of the cirque lakes, water is soon churning again, dashing downward many hundreds of meters to the valleys below, in rapids, cascades, and breathless waterfalls. Not surprisingly, few plants and animals are adapted to life in fast-moving water. Algae can be found covering streambed rocks and stranded, water-polished tree trunks. Securely attached by holdfasts, these small plant forms survive the rigorous stream flow that would destroy the larger vascular plants. Several species exist, from microscopic forms to branched filamentous algae whose long hairlike strands wave in the current. A surprising number of insects live on the stream bottom, finding a measure of protection from the current in the jumble of rocks. Underwater beetles live under the gravel or among the debris at the stream-edge, or cling to stones and sticks. Scurrying and creeping among the rock-crannies are the larvae of stoneflies, mayflies, and caddisflies. These and the small fish that venture up from lower lakes are the food of the water ouzel, a creature that loves the places where the waters thunder.
With the approach of one of the adults, three other heads crowd the opening, begging yellow mouths agape. Flying low, the ouzel parent zeros through the heavy spray, alighting on a slippery boulder below the nest ledge. Preparing to fly up to the nest with its load of insect larvae, the ouzel spots me across the water. At its sharp jigic, jigic alarm, the bills of the young snap instantly shut. Nervously the bird regards my close presence, dipping its entire body rapidly up and down, as if keeping time with the surging torrent. Discovering no danger, the dusky blue-grey bird bobs more slowly. The other adult, returning from an upstream forage, alights on the same rock, occasioning a new outcry from the fledglings. Each in turn, the parent In Shallow WatersLife abounds in the shallow lakes and ponds. Calm, protected John’s Lake offers a fine example of how a complex aquatic plant-and-animal community can exist in balance in a confined space. The water teems with the microscopic algae, protozoans, and rotifers that sustain the barely visible zooplankton. Dancing, flitting, hopping, and swaying through the water, these zooplankton in turn support the larger plankton-eating animals. Dragonflies and damselflies shoot past, crackling their wings, and perch in the bog grass. Looking into the shallow water, you will see a wealth of small animal life. A spotted frog swims into view, floating to the surface beside a lily pad so that its eyes protrude above the water. The ribbonlike form of a leech swims across the bottom toward deeper water. Looking closer, you see that the water swarms with bizarre shapes—water boatmen propelling themselves with oarlike appendages, a gliding mayfly nymph, then a predacious diving beetle surfacing, grasping a bubble of air beneath its shiny brown wing plates and disappearing downward again—the bubble’s edge shining silver—into the brown bottom debris. Suddenly a whirligig beetle sets the surface to spinning, wrinkling the view below. Everywhere in the water there is animal life, forms that are attached, free-swimming, crawling on the bottom, and clinging to or swimming on the surface film. The gray, slimy encrustation on a sunken log looks like a covering of lichen but is really a freshwater sponge, a colonial animal that feeds by filtering minute plankton from the water. Another attached creature is the barely visible hydra; this twig-shaped predator, related to marine jellyfish, captures water fleas and other small animals in its several poisonous tentacles. Water beetles, backswimmers, water boatmen, and many other creatures move about more or less freely in the water, propelling themselves along with jerky movements. Suspended between surface and bottom are the zooplankton, the tiny water fleas, cyclops, daphnia, and others, which feed by filtering minute algae. On the bottom and below live scavenging worms. Water striders skate on the surface film. Along the shore, frogs, salamanders, garter snakes, and water shrews are hunting. Dabbling and diving ducks patrol about, tipping or submerging for the bottom plants. Moose tracks circle the muddy shore. Beaver PondsFully 10 percent of all the present meadow area in the Rocky Mountains is estimated to have been created by beaver, the only animal besides man that engineers extensive changes in the environment to suit its own needs. When beavers dam a stream, they set in motion another form of succession. If the resulting backwater floods a forest area, the trees are soon killed, creating a broad opening in the forest canopy. Water-associated plants and shrubs quickly invade the pond and shoreline, creating favorable habitat for waterfowl, moose, blackbirds, amphibians, wading birds, warblers, marsh hawks, and a score of other animals. After many years the water becomes shallow, filling in with silt and plant debris. When the beavers abandon the site, the dam may rupture for lack of maintenance and the pond will rapidly drain. Or it may continue to hold, delaying for several more years its slow conversion to meadow. Stimulated by the nutrient-rich mud, the water grasses, sedges, and shrubs finally choke the water with their accumulating debris, transforming the area into a bog. Gradually the ground firms as more humus is created and more silt is trapped. The area becomes meadow, supporting grasses, sedges, and other flowering plants. Trees begin to reinvade the drier ground, and eventually the meadow reverts to forest. Centuries may be required to see this cycle through, from forest to pond, to bog, to meadow, to forest again. At each stage many of the animal inhabitants change: the song of the western robin and the chatter of a red squirrel in the original, pre-beaver forest give way to the croak of a heron; the heron is replaced by the insect-and-berry-eating cedar waxwing; the waxwing is followed by the tree-dwelling western robin and red squirrel. Lakes Cold and DeepSeeming to skate on its own reflection, a spotted sandpiper comes in low over the quiet water, wingtips almost touching the surface of the lake. It alights at the shore and folds its wings. Amid the rounded rocks, this plain but elegant little shorebird is all but swallowed up. Teetering constantly on long legs, it sets off along the water’s edge, pecking here and there, coming closer and closer, never forgetting to stop and curtsy, as if acknowledging, while hurrying offstage, the applause of an audience. As it draws near, several water striders skate away from the shore. A stonefly, scuttling between two rocks, is deftly speared. So large a morsel makes the bird I am sitting at the foot of Lake McDonald, watching the darkness gather over the valley, seeing the last light slide upward to the tips of the distant mountains. As daylight dissolves, this long fleet of familiar peaks seems almost to glide toward darkness, slow and silent as sailing ships. The sheet of motionless water stretches many kilometers away between tree-covered moraines. The water is deep and cold. No emergent plants line the barren shore. It would seem that no life, except for the single gull that rests on the water far away, exists in this nearly thousand-meter-high lake.
Contoured like bathtubs, these steep-sided lakes exhibit narrow or non-existent shoreline shallows, which are vital for the production of rooted plants. Strong wave action and extensive seasonal fluctuations in the level of these natural reservoirs prevent the development of emergent water plants in locations where they might otherwise be expected. Since sunlight cannot penetrate to the bottom of these deep lakes, they are deprived of bottom-anchored plants in midlake as well. As a result, herbivorous animal life must depend almost wholly on algal growth. Wave action inhibits the spread of free-floating algae by washing much of it onto the shore. Deep lakes are also low in available oxygen, preventing the development of bottom decomposers, which would rapidly release nutrients as they break down the accumulating debris washed into the lake. Without a steady supply of nutrients, plant growth is retarded. Since the food chain depends upon green plants, the ability of a lake to support higher animals such as fish depends upon its ability first to produce adequate plant growth. The production of one kilo of trout requires that a lake produce about 1,000 kilos of plants to support 100 kilos of herbivorous invertebrates, which are eaten by 10 kilos of carnivorous insects, on which the trout feed. Compared to smaller shallow lakes, which teem with visible life, cold, deep, nutrient-poor lakes such as McDonald appear to be watery deserts. Yet because of their great volume—Lake McDonald contains 5 or 6 cubic kilometers of water—these large lakes do sustain significant numbers of fish. Of the 22 kinds of fishes found Through the stocking of nonnative species, including plantings in formerly fish-free lakes, the natural aquatic communities of many of Glacier’s lakes and streams have been permanently modified. Aquatic food chains are not confined to the water. Ospreys, ducks, mergansers, otter, mink, and many other semi-aquatic or terrestrial birds and mammals utilize the plants and animals of the water. In fall, a remarkable spectacle occurs along the outlet of Lake McDonald. Attracted to the kokanee salmon concentrations, which run from Flathead Lake to spawn and die in these clear, shallow waters, bald eagles collect to exploit the vulnerable fish. In 1977, 444 eagles were counted in one census. This food resource is also exploited by grizzlies, coyotes, skunks, gulls, loons, and other animals. On occasion, even white-tail deer have been observed swallowing salmon! |
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