. The Canadian field-naturalist. Winter Habitat Preference of Porcupines in the Southern Alberta Foothills Don Gill' and Lawrence D. Cordes' ^Department of Geography, University of Alberta, Edmonton, Alberta ^Department of Geography, University of Calgary, Calgary, Alberta Abstract. Isolated stands of limber pine {Pinus flexilis) that occur on windswept ridge crests in the southern Alberta foothills create islands of winter habitat for porcupines {Erethizon dorsatum). The dwarfed and stunted growth-form of this tree pro- vides cover, while the high nutrient content of its bark makes it a prefe
. The Canadian field-naturalist. Winter Habitat Preference of Porcupines in the Southern Alberta Foothills Don Gill' and Lawrence D. Cordes' ^Department of Geography, University of Alberta, Edmonton, Alberta ^Department of Geography, University of Calgary, Calgary, Alberta Abstract. Isolated stands of limber pine {Pinus flexilis) that occur on windswept ridge crests in the southern Alberta foothills create islands of winter habitat for porcupines {Erethizon dorsatum). The dwarfed and stunted growth-form of this tree pro- vides cover, while the high nutrient content of its bark makes it a preferred source of winter food. Reduc- tion in predators during the past half-century has apparently enabled porcupine numbers to increase to the point where they are now threatening the existence of limber pine. These trees occur as an unusual low- elevation krummholz, and may thus have value to man as an aesthetic resource; if these limber pine stands are to survive, control of porcupine numbers may have to be initiated. Introduction Most of the fescue grassland prairie in the foot- hills region of southern Alberta has been modi- fied by ranching and farming activities, and little of the original vegetation remains. Along ridge crests and valley bottoms in the western foothills are islands of relatively undisturbed vegetation, however, that provide habitat for a variety of animals. The purpose of this paper is to describe how one animal, the porcupine, utilizes these islands of habitat during winter. Of greatest interest is the winter feeding acti- vity of this species in its almost exclusive use of the bark of limber pine where it occurs as a krummholz growth-form on exposed ridges. Study area: Methods This study was conducted in southwestern Alberta (Figure 1) during the winters of 1970- 71 and 1971-72. Food habits and movements of porcupines were determined by tracking animals during 27 days from November through March of both winters; this was done during periods when fresh s
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