Reindeer Use of Alpine Summer Habitats

Skarin, A. 2006. Reindeer use of alpine summer habitats. Doctoral dissertation. Alpine areas in the Scandinavian mountain region are used for grazing by semi-domesticated reindeer (Rangifer tarandus tarandus) during the snow-free season. These areas are also used for outdoor recreation and tourism. In summer the reindeer seek nutritive forage and relief from insect harassment during warm weather. Their habitat selection is also expected to be affected by human occurrence in the ranges. Knowledge of reindeer habitat use is needed in management, both within reindeer husbandry and society as a whole. This thesis presents research on habitat selection by reindeer at the landscape level within three temporal scales (whole summer, four summer periods, and daily cycles). The study was conducted in four study areas (210 to 4000 km 2 each) within three reindeer herding districts in Sweden: Idre Nya Sameby (62°00'N), Handölsdalen (63°00'N) and Sirges (67°00'N). The study areas differed in topography, relative abundance of vegetation types, and occurrence of back-country hikers. The reindeer habitat use was surveyed with pellet-group counts and with 48 adult female reindeer equipped with GPS collars. Reindeer preferences for different habitat attributes and reactions to hiking trails were analysed by fitting resource utilisation functions and by analyses of reindeer movements. The reindeer showed a general preference for high altitudes at all temporal scales. Selection for high-quality vegetation types was shown, in the reindeer home ranges within the periods, with preference for meadows, grass heath, and heath. The reindeer seemed limited in their forage intake by insect harassment. Effects of hiking trails were small, but the reindeer movement rates increased close to hiking trails in areas with low frequency of hikers. In areas with a higher number of tourist-reindeer encounters the reindeer seemed to have habituated to the hikers. When insect relief areas coincided with high abundance of hikers, the reindeer seemed to accept human disturbance in order to get insect relief. Predictions of habitat selection evaluated by cross-validation of estimated resource utilisation functions showed fairly low predictive capacities with the high resolution of habitat attribute data. For management purposes the results are suggested to be converted to a value point system for range compartments.