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We collect hair samples of mammal species to obtain information on their assimilated diets through stable isotope analysis. Hairs maintain an isotopic record reflecting the average diet in the whole period of the hair growth. Additionally, we also collect samples of bear hairs to obtain information on bear population size through genetic analysis. The analysis of DNA extracted from hair follicles yields information about the bear that left the sample (individual identity, gender, and potentially, kin relationship to other bears). The combination of isotope and genetic data may yield information on the assimilated diet of individual bears.

We collect hair samples in the field (e.g. left in forest fences, from dead animals) and from hunters. In the case of bears, we obtain the hair samples by hair trapping, a non-invasive method. Hair traps are placed at sites frequented by bears and uniformly distributed throughout the study area, in a grid of 10 x 10 km, typically close to ungulate feeding sites. Each hair trapping site consists of several types of barbed wire hair snags. One of them is the so-called “corral”, which consists of 25-30 m of a single strand of barbed wire stretched around trees at a height of 50 cm, with a non-consumable liquid scent lure placed on a pile of debris in the centre. Bears deposit hair on the barbs as they cross under or over the wire to investigate the scent. Another type of hair trap is simply a strand of barbed wire stretched across an animal trail at a height allowing the bears to leave the hair when passing. The last type of hair trap is a rub tree, which exploits the natural rubbing behaviour of bears. We attach short strips of barbed wire to both naturally-occurring bear rubs and trees with a special scent attractant. The samples need to be collected from the barbs ca. every 14 days.









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