Mammals of Mount McKinley National Park

by Adolph Murie

The annual berry crop is bounteous and is an important source of food for a host of birds and mammals. Even the mountain sheep have been found enjoying the blueberries. Blueberry, crowberry, cranberry, buffaloberry, and alpine bearberry are all widely distributed. The berries begin to ripen in late July.

With the melting of the snow in the spring, the white landscape of winter is transformed into a brown countryside—brown grasses, sedges, and leafless shrubbery. Snow fields still persist on the mountain slopes, and the spruces are dark green, but brown hues seem to dominate one’s impression of the tundra at this time. In June—the time varies a little with the year—the landscape is magically transformed from a dull brown to the brightest green. Early in August spots of red and yellow colors begin to show. By late August and early September the country is again transformed and we have a world of crimson and other shades of red, trimmed with yellow and gold of willow, aspen, and cottonwood. The alders add contrast for they remain summer-green throughout the autumn color season.

Over much of the country the ground remains frozen below a depth of a few feet. In some shaded areas where the ground is deeply carpeted with moss the soil remains frozen within less than 2 feet of the surface. The continuous thawing of the soil in summer keeps the surface moist until autumn. The thawed surface soil tends in places to creep imperceptibly down slopes as it becomes water-soaked, even though plant life has a strong stabilizing influence. Occasionally the soil becomes saturated with moisture to considerable depths and we have rather large land slides such as the one that recently formed Slide Lake on Stony Creek; the one that shows prominently on the south slope of Sable Mountain; and one to the south of the road at about 3-Mile that caused spruces to lean in various directions. Thawed, water-logged surface soil rests uneasily on the frozen sub-stratum.

Typical glacial stream. Grizzlies and caribou may often be seen in the streambed and Dall sheep on the mountain slopes.

A number of parallel, northward-flowing streams head in glaciers lying along the north slope of the Alaska Range. The streams are not large—most of them can be waded without getting too wet—so it is surprising to find them bordered by wide gravel bars. This is due to lack of stream stabilization. In summer the streams carry a load of silt which may be dropped along the way. Channels are continually being gouged out here and filled in somewhere else so that the stream keeps breaking over its sides and forming additional channels. High water, due to a warm day and much glacier melting, or to heavy rains, may cause the streams to flow into entirely new channels. When the main stream reaches the side of the gravel bar it will erode the bank and thus broaden the river bar. This type of erosion is noticeable just below the Teklanika bridge. Gravel bars that have not been invaded for a long period may become covered with vegetation, and it is on some of these old bars that we often see grizzlies digging roots in the spring of the year. But even these bars are temporary. One such bar on the Toklat River was invaded by part of the river a few years ago and much of the sod is being washed away today. Physiographic processes are all very active in the region. On many slopes we see the turf breaking away, and here and there a small land slip.

Typical ice blister.

Those who come to the park the early part of the summer may see extensive fields of ice on the river bars. These are the result of what is called overflow. During cold weather the ice on the streams freezes so thick that there is not room for all of the water to pass under the ice, and since it must run somewhere it develops pressure and breaks out on the surface where it spreads widely underneath the snow. Here it freezes. This process continues throughout the winter and often forms ice patches many feet thick. When one is dog-mushing on rivers the overflow water under the snow is a hazard before it freezes, and the driver of a dogteam must watch to avoid such spots. Conditions are worst during the coldest weather, at a time when a wetting is most serious.

Out in the park there are no trails except for one down Savage Canyon. The country is so open that trails are not needed. The river bars furnish excellent hiking, and even walking across the upland tundra is easy. A number of campgrounds are located along the road between the Nenana River and Wonder Lake.