Part 8

The beaver is the largest North American rodent, and the species found in Mount Rainier National Park is the largest of any of the recognized geographical range. An adult will weigh thirty pounds or more, up to a maximum of sixty pounds. The form is robust; the tail is broad, flat, and scaly; the ears are short; the hind feet webbed. The pelage is composed of short, soft underfur, with long guard hairs. The sexes are alike in size and color, a dark, glossy, reddish brown above, lighter brown below. The beaver is aquatic in habit.

Specimens in park collection: Mounted specimen, Longmire Museum, Park Headquarters.

The geographical range of the beaver extends over most of North America from the Rio Grande northward.

Beaver are not now abundant in the park, and it is doubtful that they were ever numerous. Observations have been made in many sections, notably Fish Creek, Tahoma Creek, along the Nisqually River from the park entrance to the mouth of the Paradise River, Longmire Meadows, the Ohanapecosh River, and Reflection and Tipsoo Lakes. Records indicate that Fish Creek and Tahoma Creek are the sites most extensively used by beavers during recent years, although intermittent activities have been noted in the vicinity of Longmire Meadows. A colony on Kautz Creek was undoubtedly destroyed by the flood of October, 1947.

No other animal played as important a role in the early history and exploration of this country as did the beaver. This is particularly true of the Rocky Mountain west, and to a lesser extent of the Northwest. The fur trade made the beaver pelt a standard of exchange, and to get beaver the trappers moved westward, seeking out this valuable animal in the most inaccessible and remote regions. These early explorations, which had as their incentive fur rather than the expansion of territory, paved the way for later settlement by those seeking new lands and a better livelihood in the West. So great was the demand for fur that the beavers, in the beginning abundant, were reduced in numbers to a point where returns did not compensate trappers for the risk and hardship involved.

The first mention of beaver in the park is found in Mammals and Birds of Mount Rainier, Taylor and Shaw, which states:

“Dr. A. K. Fisher records that several beavers lived at Longmire Springs until 1896, when a trapper killed them all.”

By 1905, according to the Annual Report of the Secretary of the Interior, beaver had been exterminated within the boundaries of the park.

However, by 1919, beaver were again active on Fish Creek, along the eastern base of Mount Wow, and in December, Mr. Roger W. Toll, park superintendent, reported two dams, each 100 to 200 feet in length. Mr. Toll’s observations were set forth thus in a letter:

“The beavers are now living in these lakes, and fresh signs are abundant. There are numerous tracks in the snow leading from the lakes to the thickets of alder, elder, and willow which they are eating. There is no typical beaver house in the lakes, but the under-water entrance to their house can be seen leading under the roots of a fir tree about four feet in diameter that stands on the edge of the upper lake.”

It is in this immediate vicinity that fairly extensive beaver workings were observed in November, 1947, including newly repaired small dams and fresh cuttings.

The house or burrow in the stream bank studied by Mr. Toll appears typical of the beaver in this area. In other sections, notably Rocky Mountain National Park, Colorado, where beavers are abundant, an extensive system of dams and canals is frequently developed on the smaller streams, with a large house completely surrounded by the impounded water a central feature of the colony. No such elaborate workings have been found here. Since the beavers habitually reside in burrows along the margins of streams they are referred to as “bank-beavers.” A plausible explanation for this habit is the constant and ample flow of water, which eliminates the necessity for large dams, and is adequate to cover at all times the underwater entrances to the burrows.

A small stream, bordered by cottonwood, alder, and willow, tracing its course through swampy places or meadow lands at intervals, is the preferred habitat of the beaver. The bulk of its food is made up of the bark of the tree species mentioned above, although coniferous trees are sometimes used, perhaps as an appetizer. The roots of aquatic plants are eaten also, as well as the smaller roots of tree species. In an active beaver colony, freshly peeled twigs and branches will be found lodged against the upstream side of the dam, as well as along the stream and pond margins.

Much has been written concerning the sagacity, engineering ability, and industry of the beaver. Certainly “busy as a beaver” is an apt comparison for the industrious. The amount of tree-felling, food harvesting, and construction and repair which a colony of beavers will accomplish overnight is remarkable.

Other characteristics, while impressive, are not the unerring instincts that were often attributed to the animal by early writers. While the dams are in most instances sturdily constructed of brush, small stones, mud, and, at times, sizeable short lengths of trees, a sudden spring freshet may completely destroy a poorly located structure. That the beaver exhibits what might be considered good judgment in taking advantage of natural stream barriers in dam construction is commonly demonstrated, however. It is not unusual to find trees that have fallen across water courses, or boulders in or on the margins of streams, used to provide a portion of a dam, apparently by design rather than by accident.

The felling of trees is approached in a haphazard fashion, without regard to the direction of fall. It appears that the beaver, or beavers, set to work to gnaw the trunk through at a comfortable working height above the ground, a point they can reach from a sitting position. Where the tree falls is left entirely to chance. There may be a half circle of open space in one direction, yet it is quite possible that the tree will topple in the opposite direction and so lodge before it reaches the ground. Under such circumstances the beavers may cut another section or several sections from the butt of the tree, without eventually accomplishing their purpose.

Nevertheless, to give credit where credit is due, it must be admitted that the beaver is unique in the animal kingdom by virtue of its feats, even though these are largely the result of instinct.

Among the natural enemies of the beaver clan are listed most of the predators; fox, coyote, cougar, bear, wildcat, and where their habitats coincide, the otter. It seems that all of these exhibit a liking for the flesh of this largest of rodents, although a painstaking stalk, consummated by a swift rush or leap is necessary for success, lest the beaver escape to his natural refuge, the water. The otter, of course, may enter the burrow or house and kill the young, but it is not likely that it has the strength required to deal with a full grown animal.

MOUNT RAINIER APLODONTIA, MOUNT RAINIER MOUNTAIN BEAVER Aplodontia rufa rainieri Merriam

A stout-bodied rodent, about the size of a muskrat, with a tail so short that it is concealed in the fur. Sexes are alike in size and color; upper parts light brown with a darker overcast, under parts a dull brown, sometimes showing white patches. Eyes and ears small.

Specimens in park collection: RNP-80, RNP-104, and a mounted specimen, Longmire Museum, Park Headquarters.

The various subspecies of aplodontia are found only along the western coast of North America, from the mountain ranges westward to the Pacific. It is not known to occur elsewhere in the world.

The Mount Rainier mountain beaver is found only on and in the immediate vicinity of Mount Rainier, where it is abundant in some localities from park boundaries to 6,000 feet. It has been reported from the Paradise River (5,200 feet), Longmire, Reflection Lake, Ohanapecosh, Comet Falls, the Rampart Ridge Trail, the Nisqually Entrance, in the Nickel Creek burn, and on the Wonderland Trail on the north side of Stevens Canyon (3,000 feet).

The common name of this animal is not particularly appropriate, since it resembles the muskrat and pocket gophers in appearance and habits more closely than it does the beaver to which it is not closely related. It prefers a wet habitat, but is not aquatic. It occasionally gnaws through the small stems of willow, alder, and other shrubs, felling them to the ground, but it makes no attempt to construct dams or canals. Tiny rivulets are often diverted to flow through the mountain beaver’s burrows, perhaps by accident, possibly because the animal intended such diversion.

The food of the aplodontia includes almost every succulent plant found in the park, as well as many shrubs and the bark of some trees. Bracken appears to be on the preferred list. During the summer months the presence of the animal in a locality is often indicated by bundles of plants cut and piled in exposed places to cure. The mountain beaver is more particular in this respect than the pika, the bundles are often rather neatly arranged on a log or stump, the base of the stems at one end of the pile, nicely evened up, and the entire bundle intact. After curing, the bundles are stored in the burrows, to serve as food and nesting material.

A rather extensive system of burrows from a few inches to a foot or two beneath the surface, and piles of freshly excavated earth are also evidence of the workings of this animal. The typical site chosen for development is ordinarily moist, probably not because the aplodontia is a lover of water, but because it is in such locations that suitable food plants abound. The burrows are constructed as exploratory routes in foraging, with what appears to be a main gallery intersected by a number of branches. These burrows emerge in thick cover or under logs, with the openings often connected by well-beaten runways where the overhanging plants and shrubs afford concealment.

Such extensive workings were found along the Wonderland Trail in Stevens Canyon in 1947 and 1948. The first indication of the activity of mountain beavers was the undermined condition of the trail in several places, where burrows crossed under the path and caved beneath the feet. Upon investigation many freshly cut stems of bracken were discovered, and several piles of recently excavated earth, in some instances sufficient to fill a bushel basket. This site was typical: excellent cover; several small streams; and deep, very moist soil with few rocks and an abundance of food plants.

Natural enemies of aplodontia undoubtedly include nearly all of the predatory animals, particularly the skunks and weasels, which can invade the dens without difficulty.