Ecological investigations of the tundra Ecological investigations of the tundra biome in the Prudhoe Bay region, Alaska . ecologicalinvest00brow Year: 1975 162 (c) Habitat use. Observed movements of caribou under insect harassment were not ran- dom in the Prudhoe Bay area. With the first indication of insect activity, grazing caribou would orient into the wind, but would otherwise remain grazing on the flat plains which consti- tute their major habitat. However, in their graz- ing patterns, they would avoid marshy areas and the lush vegetation of lake edges where mosqui- tos were more trouble
Ecological investigations of the tundra Ecological investigations of the tundra biome in the Prudhoe Bay region, Alaska . ecologicalinvest00brow Year: 1975 162 (c) Habitat use. Observed movements of caribou under insect harassment were not ran- dom in the Prudhoe Bay area. With the first indication of insect activity, grazing caribou would orient into the wind, but would otherwise remain grazing on the flat plains which consti- tute their major habitat. However, in their graz- ing patterns, they would avoid marshy areas and the lush vegetation of lake edges where mosqui- tos were more troublesome. Marsh & lake Plains Gravel & sand Sand dune edge veg. veg. veg. (no veg.) Increasing level of insect activity At an increased level of harassment, groups moved more quickly, heading toward areas of tundra with the least insect activity. Thus, inland groups moved north into the wind toward the coast, where the prevailing north wind reach- ed its maximum velocity. During this movement, caribou frequently moved along river beds and on the numerous game trails. In the coastal areas, the caribou would find optimum relief by lying or standing in the wind-oriented 'gullies' of the sand dune area or on the extensive sand or gravel bars of the river deltas where lack of plant growth was not conducive to mosquitos, or even by standing in the open water of the rivers and the Arctic Ocean. If harassment was not too severe at the coast, the caribou would remain there, grazing on the plants of the dry sand dune areas. Under mild harassment, caribou would often remain on the flat plains which constitute the major habitat. As insect harassment declined, normally in association with a reduction in air temperature or an increase in wind velocity, herds would leave the coastal area and slowly move inland, with concentrated grazing and dispersal into smaller-sized units, and males and females in increasingly segregated groups (Fig. 5). Follow- ing several days of freedom from insect harass-
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