Part 4

In winter, the rabbits feed on bark gnawed from various shrubs and saplings. Willow, dwarf birch and alder, because of their high palatability and abundance, are especially important winter foods. In years of rabbit abundance, I have seen patches of willow and dwarf birch trimmed to the snow line. At such times large willow brush may show a white band 2 feet wide where the rabbits have gnawed the bark within reach of the snow line. As the snow deepens, some foods are buried but the change of level brings new food supplies within reach. A variety of other shrubs are also eaten at this season. Spruce bark is relished. Porcupines, and also red squirrels, feeding in a spruce tree inadvertently add to the rabbit menu many dropped spruce twigs. In summer, the rabbits turn to a variety of fresh green foods.

The young of the snowshoe rabbit are furred and active when born and apparently there is no real nest provided. (In the cottontail branch of the family the young are born hairless, helpless and in a warm nest.) The litters may vary from one to six. The gestation period is about 36 days. The young are weaned (in captivity) when about 4 weeks old. The females breed again soon after a litter is born. It seems likely that a female may have as many as three or four litters during a summer. A male is apparently with a female for only a short time.

A number of animals are subject to cycles of extreme abundance and scarcity. The pendulum swings from one extreme to the other. A population, in spite of enemies of all kinds, increases until the numbers become so large that they threaten the food supply or, because of congestion, are drastically reduced by diseases. The length of cycle in a species depends upon annual losses and the rate of increase. Cycles are relatively short in voles and lemmings which breed at an early age (a few weeks), breed often, and have large litters. In these small rodents the cycle may cover a span of about 4 years. In larger species, the cycles are longer.

The snowshoe hare is one of the more obvious examples of a cyclic species. From acute scarcity the population in about 10 years pyramids until the country is full of rabbits. The woods are alive with a variety of activity. Enterprise, lovemaking, and tragedy are at their peak. Not only have the rabbits multiplied, but their enemies have flourished, and the lynx, fox, wolverine and birds of prey have all prospered, and certain enemies such as the lynx, become especially abundant.

During the high rabbit population peak, between 1953 and 1955, a few dead rabbits began to appear in the summer of 1954. In early August a group of tourists on a short walk noted three dead rabbits in the hotel area. But the rabbits were still numerous in the spring of 1955 and I anticipated the woods alive with young rabbits the following months. Instead, they decreased. By July, along Igloo Creek, they had become scarce. The so-called rabbit crash had taken place.

Nature steps into all situations, and one control or another automatically appears. Food shortage, disease, predation or competition enter the picture. Adjusting is a continuous process. Many people are talking and writing about the human population explosion in our midst, fearing that space for ourselves and nature is disappearing alarmingly. Perhaps we should consider the snowshoe rabbit.

Collared Pika _Ochotona collaris_

The pika, cony, or rock rabbit, as he is variously called, makes his home in rock slides. His way of life, and his physical attributes, are such, that he would have difficulty surviving away from the labyrinth of passages in his slide rock home.

The pika is in the same order (different family) as hares and rabbits. Like rabbits, they have two pairs of upper incisors; back of the grooved anterior incisors is a pair of very small incisors. The feet are furred; the ears are not long but are rounded and prominent. Something has happened to the external tail for there is none. The tail vertebrae lie under the body skin. The plump body is about 6 or 7 inches long as the cony sits on a rock; the color is gray.

The call is a single nasal “yank,” usually uttered while perched on a rock where he can look around. He may be difficult to locate, but a movement as he disappears in a crevice and reappears on the same rock or one nearby will reveal him. Usually other calls from various parts of the rock field will indicate the location of other pikas.

The pika is known for his hay making in preparation for the long winter. During much of the summer he is busy carrying grass, herbs, and twigs to his many caches located in cavities protected from the weather. The vegetation is usually added slowly enough to the various caches so that it all cures properly. Only occasionally is a cache moldy. I have noted a few caches composed of the broad, heavy coltsfoot leaves that had failed to dry properly; possibly these slow-drying leaves were harvested in wet weather. Nearly all plants within range of his rocky habitat are used. Willow, rose, grass, sedge, horsetail, various saxifrages, fireweed, coltsfoot, fruiticose and even crustose lichens are some of the many plants that have been found in the caches. Some books say that the hay is spread over rocks to dry and then stored. The pika’s technique is superior to such quick drying, and results in more nutritious and greener hay.

The sheep, moose and caribou often seek mineral licks consisting of clay which can be readily eaten. Ground squirrels and marmot feed on pebbles or fine dust in their craving for minerals. On one occasion I watched a pika gnawing a rock. A niche showed that a considerable amount of it had been eaten. I carried the rock away as a sample of rock-eating but later thought better of it and returned it to the pika. Perhaps in the future I may be able to check the rock again.

Along the road, the first good place to look for pikas is in the jumble of rocks above the Savage River bridge, an accumulation that has fallen away from a rocky point, part of which is still in place. On Polychrome Pass are several rock fields where many pikas are living. Another pika place along the road is a mile or two beyond Camp Eilson. A pretty picture is a pika carrying a bouquet of flowers, neatly arranged, as though he were going a-courting.

Hoary Marmot _Marmota caligata_

The hoary marmot is an amplified version of the eastern woodchuck. It is roughly bicolor, being gray over the shoulder region and light brown over the hips. The black patch across the nose enhances its facial aspect somewhat, and the jet-black feet add a little contrast to its appearance. He has a bushy tail that he jerks about a good deal, especially when he travels. Occasionally, he is mistaken for a wolverine. His soft color pattern is an excellent example of camouflage and of this he apparently is aware as he flattens himself on a rock to escape detection.

His voice is exceptional. One day, some years ago, I walked down Savage Canyon with two companions. One of them, who stopped to photograph some flowers, was left far behind. When he finally overtook us he said that he had heard us whistling and had hurried as best he could. We said we had not whistled, but he was still sure he had heard us. Then it dawned on me that he had been hearing the loud piercing, prolonged warning whistles of the marmots that make their homes in the canyon. This whistle is one of the familiar sounds in marmot country. The approach of a fox, grizzly bear or golden eagle is announced by loud whistling which alerts everyone, including ground squirrels and mountain sheep, to be on their guard.

One day three of us watched a youngish marmot high on a sheep ridge. He was apprehensive and for a time whistled at intervals. When one of my companions whistled in the same key, the marmot answered. But if the imitation were off key there was no reply. The marmot responded as long as our patience held. This instance may have been exceptional for I have had no opportunity as yet to make additional observations.

The marmot has learned to seek a home in a rock fortress as a safeguard against being excavated by a grizzly. Whenever possible the dens are dug in rocky areas, or at rock outcrops. One den on a steep slope that I observed for several years was enlarged and renovated each year. The small rocks encountered in the digging were carried out in the mouth and dropped on the edge of the mound. In late summer, mouthfuls of dry grass are carried in for the winter hibernating nest. One look at the broad, fat marmot suggests that he could sleep a long time without food. When he retires, he may plug the entrance with rocks and mud.

The home life of the marmots has not been carefully studied but they seem to live in colonies, all using a number of dens distributed as much as 200 yards or more apart. I have seen several adults in a colony and watched them move from one den to another. In traveling between some of the dens the marmots are highly vulnerable if surprised by one of their enemies. The attractive black-eyed young require two or more years to gain the dimensions and weight of their elders.

Two excellent places to find marmots along the highway are the jumbled boulders on the east end of the Savage River bridge and in Polychrome Pass, especially on a gray, lichen-covered rock below the road and the rocky ridge across the ravine from it. If not active, the marmots may generally be seen flattened out on a rock, basking in the sunshine.

Some of the marmots in these places and also in remote areas are quite tame. I walked practically alongside one big marmot as it fed in a patch of mertensia. It gobbled up dozens of the big leaves and chewed them down lustily and noisily, scarcely regarding my presence. Accustomed to harmless mountain sheep and caribou, they sometimes apparently place humans in the same category.

Arctic Ground Squirrel _Citellus parryi ablusus_

The most neighborly animals in the park are the ground squirrels. They quickly become tame at cabins and campgrounds and eagerly stuff their cheek pouches with hotcakes until their gulps become ludicrous with excessive efforts to make room for one more mouthful. Leave a cabin door ajar and the bread supply is soon being appropriated.

Ground squirrels are always standing erect shouting worried warnings of danger. Much of the time the cries seem to be only an outlet for accumulated nervousness. But one learns to differentiate these cries from those delivered in dead earnest. When extreme anxiety is unmistakable, it pays to become alert. Their cries have often served to call my attention to passing grizzlies, wolves, foxes, lynx and low-flying eagles. And the whole wildlife community similarly benefits. The message is relayed in all directions by ground squirrels in a sort of chain reaction, but emphasis in delivery gradually decreases until the message is lost. The cheery calls and sharp warnings of the ground squirrels are for many of us, closely associated with the general flavor and enchantment of the north country.

The winter months are spent hibernating in a burrow, curled up in a grass nest. A few squirrels remain active until the middle of October or even later. In the spring some come forth in April. Where deep snowfields cover the dens and it seems unlikely that much temperature change could penetrate to the squirrels, they nevertheless awaken as though provided with alarm clocks and tunnel to the surface. Their muddy tracks radiate from each den over the snow as the squirrels seek exposed forage.

General observations indicate that the female has only one litter each breeding season. The young do not reach adult size by the first autumn. Year after year, the ground squirrel population in the park is high. Yet no indication of cyclic behavior has been observed. Possibly their many enemies prevent them from becoming superabundant and, therefore, subject to epidemic disease.

Ground squirrels are an important factor in the park ecology. They furnish about 90 percent of the golden eagle’s diet, and in some localities they are the chief food of the gyrfalcon. The wolf at times feeds extensively on them, and they contribute heavily, sometimes 50 percent, to the fox diet. The information available indicates that the wolverine often captures them, and with the disappearance of the rabbits, the lynx deigns to hunt them for a season. For the grizzly they furnish his most dependable taste of meat. The bears spend many hours excavating for ground squirrels.

Red Squirrel _Tamiasciurus hudsonicus preblei_

The noisy red squirrel, with his churring, chattering, and “sic-sic-ing,” lends a touch of the familiar to the northern woods. He has followed the spruces along the rivers to timberline, and I saw one a half-mile beyond timber, living perhaps temporarily, among the pikas in tumbled rocks. They are generally plentiful, but in 1956 I found them extremely scarce. A catastrophic die-off had apparently occurred in the park, and that year the squirrels were also reported scarce in other parts of Alaska.

These northern squirrels have a spruce cone economy. Even before the middle of August they are frantically harvesting spruce cones (chiefly white spruce in the park). One afternoon a squirrel worked steadily in a group of spruces for almost 3 hours, cutting cones and giving them a flip with his mouth or paws. Hundreds were scattered about under the trees, and still they continued to rain and strike the ground with dull thuds. Occasionally the squirrel seemed to get his wires crossed and, instead of dropping a cone, would run all the way down the trunk with it.

Sometimes twigs bearing a cluster of cones are nipped off. In two or three sizeable caches all the cones were in clusters still attached to twigs. Perhaps this rather efficient method of handling cones is at times accentuated by certain individuals.

In September I have seen many caches scattered about on the forest floor as though piled hurriedly as a temporary expedient. One heap measured 5 feet long, 3 feet wide and about 7 inches deep. Possibly these heaps were later stored more carefully in secluded spots with the tips of the cones pointed downward. After the cones are stored, the squirrels continue to give them solicitous care. One spring when melting snow exposed a cache of cones, they were re-cached in various places, but each cone was first bitten into, and if spoiled was discarded. About the same time another cache of cones in a burrow was also removed and stored elsewhere.

Another food item that is stored in quantity is the mushroom. Many are placed on spruce branches where, if they do get wet, they will soon dry out and remain edible, and I once found great quantities stored in a cabin.

Aside from the cached foods, the red squirrels feed extensively, at least through the winter and spring, on the buds of spruce twigs. Often you may find many twigs on the ground with the tiny buds neatly removed. In Wyoming, I have found squirrels in summer living for days on the larvae in cottonwood galls, and I suspect such food may be eaten in Alaska too, where galls are found.

Each squirrel commonly has two or more nests built of grasses, shredded bark, ptarmigan feathers, and hair of rabbits, moose or whatever is available. The squirrel piles this material on a branch until it is 2 or 3 feet high. One squirrel that I watched building a nest pushed himself into the middle of the heap. Soon the whole nest shook vigorously at intervals. Apparently he was forming a chamber.

The chatter of red squirrels, their piles of middens and their busy harvesting activities, add cheer and life to the northern woods.

Northern Flying Squirrel _Glaucomys sabrinus yukonensis_

When the gesticulating red squirrel has finished his daylight bustling and retires to his nest, the flying squirrel comes forth to take over the night, but in a gentle and quiet manner. Like the night-flying owl, its coat is soft and its flight silent.

The furred “wing” membranes on each side of the body are attached to the full length of the fore and hind legs and are supported and extended in part by a cartilaginous process growing out from the wrist. Thus when the legs are extended laterally, the squirrel becomes a glider with the most delicate and reliable controls. His sailing carries him from the top of one tree to the base of another where he checks his speed by an upward swing and alights with a soft thud. Sharp claws and squirrel agility give him the climbing ability to get quickly up a tree. Where trees are widely spaced as they are in some stands of large cottonwoods, he may in winter make a five-point landing in the snow, his broad thickly-furred tail serving as rudder and gliding surface, and to a less extent as a landing ski. I have seen tracks showing a touch and a raise before the final landing with legs drawn under; then follow long jumps over the snow to the nearest tree. The nest is usually built in a tree cavity.

Perhaps the height of night esthetics is lying in a sleeping bag under the open sky, the stars and moon lighting up the spaces between the trees, and watching a family of flying squirrels gliding overhead in their night play, their shadowy forms silhouetted against the moonlit sky.

Porcupine _Erethizon dorsatum myops_

The porcupine has been accused of being slow-witted, but we must admit that he has not done badly for he is able to lead an unhurried life in the country. His quill protection has, no doubt, decreased his need for mental activity, and his eyesight does seem deficient. But his hearing is quite keen, and judging by his nose activity it appears that his sense of smell is on the acute side. His mental and physical attributes are all based on the quill.

The upper surface of the porcupine, except for the vulnerable face, is covered with several hundred ivory colored quills, touched with black or brown, and reaching a length up to at least 2½ inches. They are needle-sharp and just back from the tip are numerous minute barbs. When the quill enters the flesh of an enemy, any muscular movement causes the quill to move forward until it emerges on the opposite side or becomes lodged against the bone or under the hide.

When the porcupine senses danger he raises the quills on his back and has his muscular spine-studded tail in readiness to flip upward. He tries to keep his rear toward the enemy and to push his head into protective brush. The quills are loosely attached to the skin so pull out readily when they stick into anything. The underside of the body, in addition to the face, lacks quills but because of the short legs, the belly region is close to the ground and not vulnerable unless the porcupine is flipped over on his back. I knew a sled dog that sometimes killed porcupines by weaving and maneuvering until he had an opportunity to grasp the vulnerable nose and thus avoid the quills. Wolves, coyotes and wolverines feed on porcupines; possibly they use a similar technique in overcoming the quill armor.

In winter the porcupine feeds extensively on the inner bark and the needles of conifers. The patches where the bark has been removed are a common sight in porcupine woods. The spruces, in the last stand of timber on the east side of the Toklat River along the road, were nearly all killed by girdling, many of them back in the 1920’s when the porcupine population was extremely high. This scraggly woods is a favorite nesting area for pigeon hawks, sparrow hawks, magpies, and shrikes so that porcupine activity that seemed generally harmful has been highly beneficial to these species. Many porcupines spend the winter in a willow patch beyond the spruce and subsist on willow. For shelter in winter a windfall, hollow tree, or an old fox or wolf den may be used. Several may take residence under a cabin.

In spring I have watched porcupines climbing clumsily in tall willow brush feeding on the swollen buds. Swaying on a limb he reaches for a slender branch, pulls it to him and passes the length of it past his nose to discover the buds which he nips off. If the branch is obstreperous and cannot readily be handled in this manner, he severs it with his rodent incisors and then removes the buds as his paws manipulate the twig past his jaws. The new shoots of fireweed and other herbs are avidly sought in early summer. Willow leaves are included in the varied summer diet.

The breeding season is in the fall and the young are born about 7 months later. The usual single young one weighs about a pound, almost as much as a new born grizzly. The eyes are open, the short spines are evident, and protective reactions are soon functioning.

Their voice development is quite obvious when one or more porcupines resides under a cabin. The night moanings, squeaks of irritability, cluckings, and caressing sounds are enough to keep even the exhausted hiker awake.

Beaver _Castor canadensis_

Beavers may be found at Horseshoe Lake, Riley Creek, various ponds near the Nenana River, and in ponds and creeks along the road in the Wonder Lake region. They are out chiefly at night, but many families emerge for pond activity by 2 or 3 o’clock in the afternoon.

Beavers are large rodents, scaling 60 pounds or more. Their weight does not make them good hikers but it is no handicap in water where they paddle their way about as though they were skiffs. And when they sit up to gnaw down an aspen or cottonwood, a favorite pastime, a good solid fulcrum might be a comfortable advantage. The broad, flat, scaly tail serves as a prop when sitting erect, as a rudder when swimming, and for sounding an alarm (by slapping water) when an enemy is discovered.

The front feet are equipped with five strong toes which serve well as hands for holding twigs as the animal feeds on bark. The claws function well in all digging operations, and the arms suffice for holding gobs of mud against the chest as he pushes the load onto the dam or house. Occasionally, he carries mud in his arms as he walks up the house roof on hind legs.

The hind feet are large and webbed for swimming. Even the nails on the toes are flattened in keeping with the swimming needs. The nail of the second hind claw is double and the nail of the first toe fits down on a hard pad and is movable like a duck’s bill. These specialized claws are used for combing the fur and possibly for removing some of the large beetles that live in the fur. The prominent incisors, used for gnawing, grow continuously, as they do in all rodents, in order to compensate for wear. This is an especially fortunate adaptation for the beaver, who does so much gnawing. Otherwise his teeth would soon be worn to the gums. If an incisor for any reason is thrown out of line, so it has no surface to bite against and wear, it will become excessively elongated as it grows in a curve.