Part 5

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_.