Validation of hair tubes for small mammal population studies

Survey techniques available to sample mammals have multiplied during the last decades. They offer new opportunities for sampling and monitoring populations, but before widespread use they need to be validated and calibrated to more traditional approaches. We conducted a quantitative assessment of hair tubes designed to monitor common small mammals by comparing results to live-trapping data. Hair tubes are inexpensive, easy to use, and noninvasive, which offers benefits regarding animal ethics. We considered the shape of the tube, application in field conditions, and validated hair-tube results in 3 different habitats based on experimental and field sampling in 2 countries. Tube size selected species entering into the tubes, with shrews detected in small tubes only and rodents in larger tubes. The number of tubes visited (with hair sample) was proportional to the number of individuals captured in live traps. Overall, tubes performed better than traps, detecting individuals where traps did not, making this technique promising for inventory of rare species. The sampling pattern was robust across wood, grassland, and cultivated field habitats and across seasons, which suggests that the proportion of hair tubes visited is a robust indicator of relative abundance of small mammals. In the context of population studies, hair tubes cannot replace trapping because the identification of species or individuals from hair collected in tubes is difficult and costly. We recommend combining hair tubes with livetrapping for increased efficiency and before species identification based on DNA sampling is applied to large-scale population studies.