Article

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.

Download full-text

Full-text

Available from: Jon E Swenson, Sep 02, 2015
0 Followers
 · 
560 Views
 · 
215 Downloads
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Large carnivores, such as brown bears (Ursus arctos), are flagship species for the conservation of biodiversity and their reintroduction represents a strong challenge. However, the results of reintroductions have only recently been documented in the literature. Given the global decline of large carnivores, documenting the results of such attempts is crucial for future conservation management. Here we examined the reintroduction of brown bears into the Italian Alps. The majority of bears released (10 individuals) adapted well to the release area and this resulted in the increase of the brown bear population. At the end of 2012, the area with a stable presence of females was around 1250 km2 (minimum density = 3 bear/100 km2). Between 2002 and 2012, 34 reproductive events occurred and a total of 74 cubs were born, thus reaching a minimum population size of 47 individuals. No less than 21 young males dispersed into adjacent Italian regions or into other countries, such as Switzerland, Austria, and Germany. However, despite a high mortality rate and at least two cases of illegal killing reported in the last 2 years (2013 and 2014), a remarkable population growth rate (current level of 15.6%) has been observed.
    Journal for Nature Conservation 07/2015; 26. DOI:10.1016/j.jnc.2015.03.007 · 1.83 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Quantifying dispersal within wild populations is an important but challenging task. Here we present a method to estimate contemporary, individual-based dispersal distance from noninvasively collected samples using a specialized panel of 96 SNPs (single nucleotide polymorphisms). One main issue in conducting dispersal studies is the requirement for a high sampling resolution at a geographic scale appropriate for capturing the majority of dispersal events. In this study, fecal samples of brown bear (Ursus arctos) were collected by volunteer citizens, resulting in a high sampling resolution spanning over 45,000 km2 in Gävleborg and Dalarna counties in Sweden. SNP genotypes were obtained for unique individuals sampled (n = 433) and subsequently used to reconstruct pedigrees. A Mantel test for isolation by distance suggests that the sampling scale was appropriate for females but not for males, which are known to disperse long distances. Euclidean distance was estimated between mother and offspring pairs identified through the reconstructed pedigrees. The mean dispersal distance was 12.9 km (SE 3.2) and 33.8 km (SE 6.8) for females and males, respectively. These results were significantly different (Wilcoxon's rank-sum test: P-value = 0.02) and are in agreement with the previously identified pattern of male-biased dispersal. Our results illustrate the potential of using a combination of noninvasively collected samples at high resolution and specialized SNPs for pedigree-based dispersal models.
    Ecology and Evolution 07/2015; DOI:10.1002/ece3.1588 · 2.32 Impact Factor
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    ABSTRACT: It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decline or periodically disrupted dynamics in cyclic populations of small and medium-sized mammals and birds. The first warm spell, 1930–1960, stands out as a period of substantial faunal change. However, in addition to climate warming, suggested drivers of change include land use and other anthropogenic factors. We hypothesize all these drivers interacted, primarily favoring southern generalists. Future research should aim to distinguish between effects of climate and land-use change in boreal and tundra ecosystems. Electronic supplementary material The online version of this article (doi:10.1007/s13280-014-0606-8) contains supplementary material, which is available to authorized users.
    AMBIO A Journal of the Human Environment 01/2015; 44(Supplement 1):39-50. DOI:10.1007/s13280-014-0606-8 · 2.97 Impact Factor
Show more