Mammals of Mount McKinley National Park

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.

A flourishing beaver colony apparently consists of the parents, the young of the year, and the previous year’s offspring. It is for this reason that we often discover three sizes of beavers in a pond. Much of beaver activity involves cooperative projects where there is latitude for any amount of individual initiative. The dam or dams must be built, or raised, or kept in repair. The house, located either out in the pond, or partially or wholly on the shore, may require additional sticks, and toward autumn is plastered on the outside with wet mud as a sort of annual renovation. This “stucco” winterizes the lodge. Occasionally, it is decided that a new house is needed and that gives young and old plenty to do. Some beavers along Riley Creek live in bank burrows and build no dams or houses.

The most effective dam that has come to my attention was built at the outlet of Wonder Lake in 1960; it raised the water level of the lake over 2 feet. For many days the outlet stream was dry. The water held back in the lake amounted to well over 100 million cubic feet or over 7 billion pounds of water.

The water depth beside the lodge must be deepened if too shallow, so that the underwater entrance to the lodge is deep enough to keep from freezing over, and imprisoning the occupants. Also a certain depth of water is needed beside the lodge in which to store the brush pile that is the winter food supply. Another activity practised extensively by some colonies is the building of canals, some of which may have great length. The mud from the digging is deposited along the canal forming a raised border. These waterways are useful for general travel to food areas and for transporting branches and poles.

The favorite foods of the beaver include willow, aspen, cottonwood, and alder. Willow brush re-sprouts readily and grows rapidly, therefore maintains itself better than some of the other foods. Also it flourishes in the wet habitat created by the beaver ponds.

Where beavers create ponds with their dams, they produce a habitat for fish, ducks, muskrats, shore birds, moose and many other forms of water and shore life. In Wyoming, I have observed the dead trees, killed by flooding, used by herons for nesting, and one of the heron nests was later used by a pair of geese.

The rich, warm coat of the beaver has long been worn by both humans and beavers, but the beaver wears it best.

Muskrat
Ondatra zibethicus spatulatus

In some parts of Alaska where extensive favorable pond habitat prevails, muskrats are abundant and their sedge lodges are a part of the scenery. In the park there are a few muskrats in Horseshoe Lake and other ponds and creeks near the eastern border, and also in the Wonder Lake area. These usually live in bank burrows with submerged entrances. It is not uncommon to find a muskrat living in an occupied beaver house, apparently utilizing an unoccupied cranny. They ply back and forth across the pond, just as the beavers do, and submerge with a mouthful of sedge which they are taking to the young. At Wonder Lake, I have seen muskrats swimming under the little bridge across the stream inlet, carrying sedges to young that were kept in a burrow in a nearby bank of the lake.

Because muskrats are associated with beavers they are sometimes mistaken for young beavers. The longer scaly tail, that is flattened vertically rather than horizontally, serves as a certain identification. The muskrat is also much quicker in its actions, and is smaller than any beaver old enough to be abroad.

The muskrats’ chief food consists of green vegetation (various waterplants and sedges) and clams when available; it has even been reported catching small fish in some regions. Some of the deeper waterplants it secures by diving, and in the spring I have watched them climb onto the ice to eat them. A muskrat looks very tiny sitting on the ice beside a big beaver.

Muskrat have their winged and fourfooted enemies. Mink, living in the same environment, prey on them, but not indiscriminately. Other carnivores such as the fox, coyote, and wolf might encounter one on land, but chiefly by accident.

Shrews
Sorex sp. and Microsorex sp.

Shrews may be identified by their long, pointed, mobile nose, extremely minute eyes, short velvety fur and blackish-tipped teeth. They are the smallest mammals in the world, some kinds weighing less than 3 grams. It would require over 100 of these to weigh one pound. Because of the shrew’s small size and long nose, Alaskans frequently refer to them as long-nosed mice.

Thousands of shrews (four species) are vigorously active in the park but are rarely seen. Occasionally, one may be discovered crossing an open area, like a mechanical toy, or one may flash from cover and as quickly disappear. They share with the voles and lemmings the shade and darkness of the hidden runways beneath the moss and grassy cover. Here they are active predators, darting about in their search for prey. With nervous activity they examine their microhabitat in search of insects and other invertebrates. Spiders flee in haste when the presence of a shrew is sensed. Their hunting technique appears to consist of random movements until they collide with their victim. They no doubt depend chiefly upon the sense of smell in recognizing their prey.

Shrews eat often and a great deal. In captivity, a shrew weighing 3.6 grams ate over three times its weight of food daily. Any kind of meat attracts shrews, as many Alaskans have learned when discovering their meat caches invaded by them. The energetic activity of shrews suggests the need for rapid metabolism and plentiful supply of body fuel.

Although shrews are active throughout the winter, they nevertheless appear to be delicately attuned to their environment. They seem to be especially susceptible to chilling, perhaps because of their tiny body and short fur. Winter temperatures in the north are severe, but ground temperatures under the snow blanket are rather moderate. Shrews perhaps require only a warm nest—their intense activity keeping them warm when foraging.

Shrews are not rated high gastronomically by many mammals. This is apparently due to the hip glands which have a strong, pungent odor. But their lack of palatability does not give them much protection. If, for instance, a fox locates a faint sound in the grass, he pounces and learns later what he has caught. If the prey is a shrew, it may be left where killed by the fox, carried a short way and dropped, or during denning time even brought home to the den before discarded. I have often found shrew carcasses lying uneaten about fox dens. Birds of prey feed more extensively on them possibly because of their poorly developed sense of smell, and sense of taste. Grayling, and also trout, have been found with one or more shrews in their stomachs. At Moose Creek, several grayling were taken which had eaten shrews, one having eaten three of them. This indicates that the species captured, readily enter the water. (One species, the water shrew, not found in the park, is specialized for aquatic life).

The shrew population is apparently cyclic for there are years when they are very abundant, followed by years of extreme scarcity.

Four kinds of shrews are in the park. They differ from one another in several respects, but may be fairly well identified by tail length alone. The masked shrew (Sorex cinereus) has a tail averaging about 39 millimeters long; the tail of the vagrant shrew (Sorex obscurus) averages about 48 mm.; and that of the rare pygmy shrew (Microsorex hoyi eximius), 31 mm. The average length of tail of the Arctic shrew (Sorex arcticus tundrensis) is about 36 mm., overlapping slightly in this measurement that of the masked shrew, but the rich chocolate color of the Arctic shrew will identify it.

Bat
Vespertilioninae

A bat was reported in flight at Wonder Lake in 1959 and again in 1960. Since no specimen has been examined there is no definite identification, but judging from the geographical distribution of bats it seems probable that those seen in the park belong to the genus Myotis. Three or four species of this genus are known to occur in southeastern Alaska. The little brown bat (Myotis lucifugus alascensis) has been taken at Illiamna Lake at the base of the Alaska Peninsula so it seems likely that this is the bat seen at Wonder Lake.

The Mouse World
Microtinae

Are there any trails in the park? Yes, thousands of miles, but most of them are under a canopy of grass and sphagnum moss and are only 1 or 2 inches wide, so of course they are not of much use to you. And even if we could nibble on Alice’s mushroom and grow, in reverse, small enough to use them, we would hardly dare, at least a lady wouldn’t, for she would soon meet a mouse, inasmuch as these trails have been constructed by, and belong to, mice. And I might add that the fierce little shrews use them too. Where the trails cross green, mossy carpets and enter tiny exquisite nooks I imagine one might also meet a few northern fairies.

Seven kinds of mice (voles and lemmings) are known to live in the park. Some of these are quite outstanding for one thing or another, and possibly all of them are, if we only knew more about them. However, we do know that they are all important.

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I am best acquainted with the haymouse, or singing vole (Microtus miurus oreas) because some of my field observations led me to him. Some years ago I kept finding many caches of dried vegetation, some caches large enough to fill a bushel basket. This hay was always kept either off the ground or under cover. It was placed at the base of willows in the basket formed by the many stems, or on a surface spruce root, in a rock niche, or under a log. Pikas are known to make hay, but no such activity has been reported for mice. Pikas were not involved for they live in the talus rock, and these caches were mostly far from pika habitat. After considerable effort, I learned that a yellowish-brown field mouse was the interesting haymaker. The hay is put up for winter use. The sign showed that sometimes a snowshoe hare found a cache and helped himself.

In addition to hay, this mouse also stores roots in underground cellars that he excavates, and the roots are not thrown in helter-skelter, at least not in most of the caches I examined. The black, round nutlike tubers of the horsetail were in one pile, coltsfoot underground stems in another, and carrotlike roots of a pedicularis in still another. An interesting feature was the structure of some of the tunnels which were built in the form of a pearl necklace. Tiny passages, just large enough for the body of the mouse to squeeze through, joined the cavities or, so to speak, the “pearls.” In addition to all of these accomplishments, these mice do much miniature warbling, enough so they have been called singing voles.

The tail is short, measuring slightly over 1 inch; the body length averages about 5 inches. It is found from moist lowland habitats to ridge tops.

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The large, plump, and richly-colored brown lemming (Lemmus trimucronatus alascensis) is notorious for his overpopulation problem. On some occasions they migrate in hordes, even into the ocean in some parts of their circumpolar home. The lemming is cyclic in the park, but usually only to about the same degree as the other mice. However, in the low part of the cycle, they may become extremely scarce, more so than do the voles. The brown lemming does not turn white in winter as does its relative, the collared lemming (over most of its range). The body is about 5½ inches long and the tail is just under 1 inch. The thumb claw consists of a three-pronged flat nail. A large lemming weighs about one-quarter pound. They are widely distributed in both open tundra and woods where the habitat is not too dry.

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The northern bog lemming (Synaptomys borealis dalli) is usually not thought of as a true lemming, but it does belong to the lemming tribe. It has a short tail, less than 1 inch long; the body length is about 4 inches; the upper incisors have a vertical groove near the outer edge; and the males have a white spot on each side marking the location of hip glands. The thumb claw is a broad nail, in this respect resembling the brown lemming. The distribution of this mouse is spotty. It was taken in the Wonder Lake area in a wet grass and sedge habitat just inside a spruce woods.

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The chestnut-cheeked vole (Microtus xanthognathus), the largest mouse in the park, has a body length of 6 or 7 inches, tail length of about 2 inches, and weighs up to about 6 ounces. These mice live in isolated colonies but where found may be abundant. Not recorded in the park since 1907 when it was abundant along the Toklat River.

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The tundra vole (Microtus oeconomus macfarlani) is a large vole widely distributed, and is especially fond of dense grass or sedge habitats. Its body length is 5 to 5½ inches, and tail length a little less than 2 inches. Its brownish-gray color is similar to the common meadow mouse.

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The meadow vole (Microtus pennsylvanicus tananaensis) is common in interior Alaska, so far as known, but is rare in the park. With more investigation, it may be found plentiful in places along the north boundary. This is a common vole over much of Canada and the Rocky Mountain, central and eastern states. It prefers moist habitats. The body length is about 5 inches, tail about 2 inches, and the color is dark brown.

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The northern red-backed mouse (Clethrionomys rutilus dawsonii) lives in both the open tundra and the woods. Generally, it has a reddish back, but in a dark color phase, the back is blackish. These mice are fond of berries, their teeth being stained blue during the blueberry season. They also feed on seeds, stems, and leaves.

The several species of mice vary in abundance from year to year. In places where some of them have been studied, a well-defined 3 or 4 year cycle has been noted. The mouse populations have a tremendous influence on our wildlife economy. Foxes, martens, weasels, owls, hawks and a host of others feed extensively on this fauna and react to its abundance. When the lemming increase in the north, the snowy owls (and others) increase, and when the lemming become scarce, these owls come south in search of food and we have the snowy owl invasions, especially in north-central and eastern states. In 1955, when mice were abundant, the hawk owls in the park reached a high point, but again became scarce when the mouse population dropped.

Checklist of The Mammals of Mount McKinley National Park

Arctic Shrew

Masked Shrew

Dusky Shrew

Pygmy Shrew

Bat (Species unknown)

Black Bear

Grizzly Bear

Marten

Short-tailed Weasel

Least Weasel

Mink

Wolverine

River Otter

Red Fox

Coyote

Wolf

Lynx

Hoary Marmot

Arctic Ground Squirrel

Red Squirrel

Northern Flying Squirrel

Beaver

Bog Lemming

Brown Lemming

Northern Red-backed Mouse

Meadow Vole

Singing Vole

Tundra Vole

Chestnut-cheeked Vole

Muskrat

Porcupine

Collared Pika

Snowshoe Rabbit

Moose

Caribou

Mountain goat

Dall Sheep

Transcriber’s Notes

• Silently corrected a few typos.
• Retained publication information from the printed edition: this eBook is public-domain in the country of publication.
• In the text versions only, text in italics is delimited by _underscores_.