Efficacy of passive hair-traps for the genetic sampling of a low-density badger population

A hair-trapping survey was carried out in the western River Po plain (NW Italy). We aimed to test whether barbed wire hair snares in combination with DNA profiling might represent an effective tool to study a low-density badger population. Traps were placed above the entrances of twelve badger setts between 15 February and 30 April 2010. Trapping effort was expressed as the number of trap-nights required to pluck a hair sample and the trend in the number of genotyped individual over time was analysed by regression analysis. Forty-three hair samples were collected, with an overall trapping effort of 54.8 trap-nights per one hair sample. Twenty-eight samples yielded reliable genotypes, allowing the identification of nine individual badgers. The length of storage period (1-3 months) before DNA extraction did not seem to affect genotyping success. According to the regression model, trapping effort allowed to sample 75% of the overall population. Our results suggest that the efficacy of passive devices is affected by population density.