Trails left by caribou on their spring, summer and fall ranges persist for many years and therefore provide useful record of patterns of caribou movement. Trails covering 15,000 km² of northeastern Alaska were mapped from light aircraft, and found to correspond with present patterns of movement of the Porcupine caribou herd. Caribou follow contours in hilly terrain; use gentle slopes and passes; travel in narrower lanes in steep areas; course natural obstacles before crossing them; and follow previous caribou trails. Areas of special importance to caribou because of funneling of their movements are identifiable from trail maps, which are therefore useful tools in the planning of proposed structures in caribou ranges.
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