Estimation of black bear (Ursus americanus) abundance in the Northern Lower Peninsula of Michigan using microsatellite DNA markers

The estimation of black bear population abundance has long been a difficult task, however valuable when justifying harvest quotas and managing populations. Recent advancements in molecular genetics have provided a means to identify bears using DNA contained in tissue and hair samples. We collected hair samples non-invasively using barbed wire hair snares and tissue samples from harvested bears to genetically identify individuals and estimate bear abundance in the Northern Lower Peninsula (NLP) of Michigan using a capture-recapture methodology. In both 2002 and 2003 we derived hair snare locations using a stratified random design and collected hair samples over a number of sampling intervals. As an additional sampling occasion we collected tissue samples from hunter harvested bears. We genetically analyzed hair and tissue samples with 5 microsatellite loci and quantified genotyping errors using samples from harvested bears. We estimated the population of yearling and adult black bears in the NLP with models that account for genotyping error to be 1,882 bears (95% CI 1,389--2,551 bears). We created a simulation model to quantify the effects of genotyping error and sub-sampling hair samples and found that genotyping error dramatically biases population estimates and the selection of 3 hair samples, when multiple hair samples were available, reduced the variance of population estimates.