Estimating population size and trends of the Swedish brown bear Ursus arctos population

[ "Jonas Kindberg & Göran Ericsson, Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden - e-mail addresses: (Jonas Kindberg)
Wildlife Biology (Impact Factor: 1.07). 07/2011; 17(Jun 2011):114-123. DOI: 10.2981/10-100

ABSTRACT Estimating population size and trends are key issues in the conservation and management of large carnivores. The rebounding brown bear Ursus arctos population in Sweden is monitored by two different systems, both relying on voluntary resources. Population estimates have been calculated using Capture-Mark-Recapture methods, based on DNA-based scat surveys in five of the six Swedish counties with established bear populations. A total of 1,358 genotypes were identified using DNA extracted from collected scats. An independent ongoing programme, the Large Carnivore Observation Index (LCOI), was initiated in 1998. The LCOI uses effort-corrected observations of bears by moose Alces alces hunters during the moose hunt (> 2 million observation hours/year) and has shown a good correlation with relative population density of bears using the DNA-based method. From this, we have calculated population trends during the period 1998-2007. Using an exponential model, we estimated the yearly increase in the bear population to be 4.5% at the national level, varying between 0 and 10.2% in different counties. We used the regional population estimates and the trends from the LCOI, taking the variation from both systems into account using parametric bootstrapping, to calculate the regional as well as the national population size in Sweden in fall 2008. In one case (the northernmost county; Norrbotten) a DNA-scat survey was lacking, so we used assumptions based on data from the neighbouring county to estimate population size. We estimated the Swedish brown bear population to be 3,298 individuals (2,968-3,667; 95% confidence intervals) in 2008. Our results suggest that reliable information, necessary for the management of the brown bear population can be obtained from volunteers using standardised methods.

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Available from: Jon E Swenson, Sep 02, 2015
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    • "Consequently, the growth rate of the subpopulation in central Austria, which probably was functionally isolated (i.e., no exchange of females) from the nuclei along the Austrian–Slovenian border, yielded some 7%. Kindberg et al. (2011) estimated that the Swedish brown bear population was composed by 3298 (2968–3667) individuals in 2008, thus reporting a yearly increase of 4.5% on the national level and from 0 to 10.2% on the county level for the period 1998–2007. This rate is comparable to that of other expanding populations in Europe (Rigg & Adamec 2007). "
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    • "Volunteers, mainly moose hunters, opportunistically collected feces and sent the samples along with the coordinates of the sample location to the county administration board (L€ anstyrelsen, Sweden). This sample collection was performed following the same protocol described in Bellemain et al. (2005) and Kindberg et al. (2011). "
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    • "All large mammalian predators, brown bear (Ursus arctos), wolf, Eurasian lynx, and wolverine (Gulo gulo), declined due to persecution in the nineteenth and early twentieth century (Sweden's Official Statistics 1870–1966). The brown bear became restricted to small parts of boreal Sweden, but recovered and spread throughout northern Sweden in the twentieth century (Kindberg et al. 2011). Likewise, wolf became restricted to alpine tundra, where a few individuals remained until extirpation in the 1960s. "
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