Genetic tagging of free-ranging black and brown bears

Identification of individuals in a free-ranging animal population is potent ially hampered by a lack of distinguishing features (e.g., scars, unique co lor patterns), poor visibility (e.g., densely forested environments), cost and invasiveness of physical capture, and mark loss; Advances in DNA-analys is technology offer alternative methods of individual identification that m ay overcome several of these problems. We investigated the genetic variabil ity of American black bears (Ursus americanus) and brown (grizzly) bears (U rsus arctos) in the ColumbiaRiver basin of British Columbia, Canada, and de veloped a method to obtain genetic samples from free-ranging bears. We esta blished the background genetic variability using microsatellite genotyping at 9 loci using tissue and blood samples from captured bears. In 3 field tr ials, we tested methods to obtain hair from free-ranging bears. Although al l methods collected hair suitable for DNA analysis, the barbed-wire enclosu re hair-trap was superior. We extracted DNA from hair roots and identified sample species with a species-specific mitochondrial DNA (mtDNA) test and s ample sex from a Y-chromosome test. Using 6 microsatellite loci from nuclea r DNA (nDNA), we screened all hair samples for individual identity and deve loped match probability functions based on scenarios of random sampling (P- random), the likely presence of parent-offspring groupings in the samples ( Ppar-offs), and the likely presence of siblings in the samples (P-sib) We a pplied the Psib to each hair sample (match criteria at P-sib<0.05) and illu strated how these microsatellite genotypes can be used as genetic tags in m ark-recapture bear censuses. The ability to identify species, sex, and indi viduality of free-ranging bears has numerous potential applications in fiel d studies.