Dall sheep are the most conspicuous animals of the alpine tundra.
Kotzebue Sound Subregion
Mammals
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Dall sheep are the most conspicuous animals of the alpine tundra. |
Habitats in this subregion vary from treeless coastal tundra to forests and alpine tundra, and all except the areas immediately adjacent to Kotzebue Sound are part of the arctic caribou herd's range (Figures 131 and 132). Most of this is wintering ground, but habitats north of the Brooks Range are predominantly used in summer. Until recently, this herd numbered about 240,000 animals, but within the past year or so their numbers have dropped markedly.
The most significant aspect of caribou use of range is their mobility and unpredictability. They may be found in most of the plant communities of the subregion at some time during the year—most commonly, the tundra types in summer and the open, lichen-rich upland spruce-hardwood forests of the major river valleys in winter. Heavy snows can force them to remain on windswept tundra. They may occupy other parts of their range one year and not to return to it for several seasons. This habit is well adapted to the slow growth rate of lichens, their major food, which could receive long-term damage from repeated grazing and trampling.
Only their calving grounds are the same every year. They lie outside this region north of the Brooks Range in the headwaters of the Utukok River drainage. The herd moves south in late August and early September and usually arrives onto the south slopes of the Brooks Range in early October. They remain on the wintering grounds until March when northward migration usually begins. In years with late spring breakup, the animals may remain in the region even longer.
Caribou are an important part of the biotic system, not only for man, but also as food for wolves, bears, foxes, wolverines, eagles, and a variety of less conspicuous birds, mammals, and finally invertebrates which complete the job of converting caribou to the organic constituents of soil.
Dall sheep confine themselves to the alpine tundra of rugged, rocky portions of the Brooks Range where suitable food and escape routes are available (Figure 132). Summer and winter ranges may be separated by several miles, and winter ranges are usually more restricted to areas blown clear of snow. Sheep also are a major resource to the biotic system, converting energy from plants to an energy source for carnivores, but because of their restricted range, their effect is minor.
Grizzly bears occur throughout the subregion, taking advantage of various habitats. Valleys of major rivers receive most intensive use. Usually these are streams with large runs of fish which provide an abundant food source in late summer and fall. Valleys of the Noatak, Kobuk, Selawik, and Buckland Rivers are the most heavily used. Bears also tend to follow beach lines, probably in search of food washed up from the sea.
Distribution of black bears is not mapped, but they occur throughout most of the subregion, usually not far from woodlands. Their habits do not differ greatly from those of grizzly bears.
Wolves, distributed throughout the subregion, may be a controlling factor on populations of caribou and moose. They also feed on a variety of other game, ranging from Dall sheep to snowshoe hares and other small mammals and birds.
Moose were either scarce or absent in the subregion until 50 to 75 years ago. Primarily concentrated in winter in timbered areas or in high willow brush along streams, they disperse widely in spring, summer, and fall throughout the subregion, wherever browse is available (Figure 129). Most important wintering areas of the subregion are in timber and brush along the Noatak, Kobuk, Selawik, and Buckland Rivers. Their major predator is the wolf, although bears may also take calves.
Muskoxen were transplanted in 1970 from Nunivak Island to Cape Thompson. These animals forage for a mixture of grasses that are blown relatively clear of snow in winter. Most of their range is along the coasts and between Cape Thompson and Cape Lisburne and in the Lisburne Hills. Scattered animals also inhabit the area southeast and east of Kivalina.
All species that appear on the lists for each plant community occur in the subregion. Wolverines are distributed throughout, feeding on whatever game or carrion is available. Some species, such as the snowshoe hare and red squirrel, are restricted to the eastern forested portion. Lynx and marten feed on these two species and are similarly distributed. Mammals of the open tundra, such as lemmings and tundra hares, are more abundant in the western treeless portion. Arctic foxes and polar bears occur along the coast, but seldom range into lands bordering Kotzebue Sound.
[Alaska Regional Profiles, Northwest Region, pp. 150-151]