The seasonal composition of and the annual variation in the diet of the brown bear Ursus arctos in the Pasvik Valley, northeastern Norway, were estimated based on the analysis of 137 bear scats. The importance of moose Alces alces and reindeer Rangifer tarandus in the diet was given special attention, because results from Russia suggest that brown bears are generally more carnivorous in the north. Ungulates, especially adult moose, comprised the most important food item for bears in the Pasvik Valley during spring and summer, contributing 85 and 70% of the Estimated Dietary Energy Content (EDEC), respectively. During autumn, when the bears have to build up fat reserves and increase lean body mass for hibernation, berries were the most important food item, contributing 49% of the EDEC, but ungulates were still important, contributing 30% of the EDEC. Insects and vegetation were of low importance in all seasons. The proportion of ungulates in the diet of brown bears in the Pasvik Valley was considerably higher than farther south in Scandinavia, and this regional difference is important concerning bear and moose management in northern areas.
Noninvasively collected genetic data can be used to analyse large-scale connectivity patterns among populations of large predators without disturbing them, which may contribute to unravel the species' roles in natural ecosystems and their requirements for long-term survival. The demographic history of brown bears (Ursus arctos) in Northern Europe indicates several extinction and recolonization events, but little is known about present gene flow between populations of the east and west. We used 12 validated microsatellite markers to analyse 1580 hair and faecal samples collected during six consecutive years (2005-2010) in the Pasvik Valley at 70°N on the border of Norway, Finland and Russia. Our results showed an overall high correlation between the annual estimates of population size (N(c) ), density (D), effective size (N(e) ) and N(e) /N(c) ratio. Furthermore, we observed a genetic heterogeneity of ∼0.8 and high N(e) /N(c) ratios of ∼0.6, which suggests gene flow from the east. Thus, we expanded the population genetic study to include Karelia (Russia, Finland), Västerbotten (Sweden) and Troms (Norway) (477 individuals in total) and detected four distinct genetic clusters with low migration rates among the regions. More specifically, we found that differentiation was relatively low from the Pasvik Valley towards the south and east, whereas, in contrast, moderately high pairwise F(ST) values (0.91-0.12) were detected between the east and the west. Our results indicate ongoing limits to gene flow towards the west, and the existence of barriers to migration between eastern and western brown bear populations in Northern Europe.
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