Fauna Series No. 3

Fauna of the National Parks — No. 3 Birds and Mammals of Mount McKinley National Park

Mammals

DESCRIPTIONS OF MAMMAL SPECIES

CANADIAN BEAVER
Castor canadensis canadensis [KUHL]

GENERAL APPEARANCE.—The beaver is the largest gnawing mammal or rodent in Alaska. The eyes and ears are small; the tail is flattened, broadly paddle-shaped and covered with scales. The hind feet are large with a complete webbing between the toes. This animal is rich reddish-brown in color. The pelage consists of long glossy over hairs and a shorter dense under fur. Body length, about 30 inches; tail, 16 inches; weight, 40-65 pounds.

IDENTIFICATION.—The heavy body, aquatic habits, scaly tail, webbed hind feet, and large orange-colored protruding incisor teeth distinguish the beaver at a glance. Beavers are nocturnal and hence are usually not abroad much in the daytime. They may be seen swimming about at dusk, their bodies submerged and only the top portion of the head showing above the water.

DISTRIBUTION.—Formerly the beavers were found in lakes and streams over most of North America. The larger rivers in the park which head in live Glaciers and are full of silt are not inhabited by beavers. Possibly they are absent from these streams because of the silt. Along the headwaters of Clearwater and Moose Creeks in the northwest portion of the park there are numerous small clear lakes and ponds inhabited by beavers.

In 1932 we found two families of beavers with several houses or lodges in ponds along the side of the main trail near the lower end of Muldrow Glacier. We also found beavers all along the creek which empties into the north end of Wonder Lake.

Figure 60.—A Canadian beaver dam on a seepage rivulet. Photograph taken July 1, 1932, McKinley Park Station. W. L. D. No. 2647.

HABITS.—Investigation showed that the building of dams and houses by heavers in the ponds of the park where these animals are found is the same as similar activities carried on by beavers elsewhere in central Alaska. Until about 1930, a family of beavers lived in a small pond between the Alaska Railroad and the Nenana River, about half a mile down the stream from McKinley Park Station. In June 1932, I found beaver cuttings, several well-built beaver dams (fig. 60), and a well-constructed beaver lodge in this pond. However, there was clear evidence that the beavers had all been killed about 18 months previous to my visit. Now that this area is inside the park, it is hoped that beavers will again be established and properly protected there.

At Wonder Lake on August 13, 1932, although it was high noon and the sun was shining brightly, I watched a beaver come out of this lodge and swim slowly about basking in the sun for more than an hour. At times this full grown beaver swam up to within 50 yards of me. He was apparently curious but when he became alarmed he did not "whack" the water with his tail. Instead he submerged quietly and swam more than a hundred yards before coming to the surface.

Within the year a new beaver house had been built at the north end of Wonder Lake. This is an ideal place for visitors to see beavers and it is hoped that these animals can he protected and kept there in some numbers.

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Last Modified: Thurs, Oct 4 2001 10:00:00 pm PDT
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