Summer feeding behaviour of reindeer

Reindeer (Rangifer tarandus L.) plays an important role ecologically, economically, as well as culturally in northern Fennoscandia, where reindeer husbandry traditionally has considered winter to be the bottleneck for reindeer. Recent studies have shown that summer feeding conditions control reindeer population dynamics through indirect effects on winter survival and reproductive success. My thesis is unique as it analyses seasonal plant nutrient dynamics, their spatial patterns and reindeer summer foraging behaviour at different levels simultaneously. The aim was to test the underlying assumptions behind the hypothesis that reindeer select the new emerging growth (highly digestible and protein rich) and move into new areas as the emergence of new growth proceeds along climatic gradients. The studies were done in a mountainous landscape of sub-arctic northern Sweden used by the semi-domesticated reindeer herd belonging to Gabna Sami community. The study on plant nutrient dynamics of four forage species (Betula nana L., Eriophorum angustifolium L., Rumex acetosa L. and Vaccinium myrtillus L.) revealed that plant nitrogen concentrations (and thus protein content) related to snowmelt patterns. It was further shown that reindeer selected areas with high landcover diversity, and thus might respond to any landscape heterogeneity that results from varying snowmelt patterns. Within landscapes, reindeer selected species rich plant communities with high abundance of preferred food plants (deciduous shrubs, herbs and graminoids) and fed where food biomass was high, predominantly that of birch and willow species. Contrary to predictions of the tested hypothesis, it was concluded that reindeer responded to food quantity rather than quality at intermediate (i.e., within plant communities) levels of feeding habitat selection. Feeding habitat selection at higher (i.e., feeding area and plant community selection) and lower (i.e., plant species and parts selection) levels indicated the importance of food quality and was thus in agreement with the tested hypothesis. My results have implications for land management as they show the importance of maintaining heterogeneous alpine landscapes for reindeer husbandry. Furthermore, reindeer husbandry needs to be practised at a level that maintain species rich and diverse plant communities. These plant communities were shown to be important feeding habitats, at the same time as they may contribute to nature conservation goals