Part 10

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.

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.

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.

Bald Eagles and Kokanee Salmon: A Recent Gathering

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.