Spatiotemporal factors affecting detection of black bears during noninvasive capture–recapture surveys

Accounting for low and heterogeneous detection probabilities in large mammal capture–recapture sampling designs is a persistent challenge. Our objective was to improve understanding of ecological and biological factors driving detection using multiple data sources from an American black bear ( Ursus americanus ) DNA hair trap study in south-central Missouri. We used Global Positioning System telemetry and remote camera data to examine how a bear’s distance to traps, probability of space use, sex-specific behavior, and temporal sampling frame affect detection probability and number of hair samples collected at hair traps. Regression analysis suggested that bear distance to nearest hair trap was the best predictor of detection probability and indicated that detection probability at encounter was 0.15 and declined to < 0.05 at nearest distances > 330 m from hair traps. From remote camera data, number of hair samples increased with number of visits, but the proportion of hair samples from known visits declined 39% from early June to early August. Bears appeared attracted to lured hair traps from close distances and we recommend a hair trap density of 1 trap/2.6 km 2 with spatial coverage that encompasses potentially large male home ranges. We recommend sampling during the late spring and early summer molting period to increase hair deposition rates.

The effectiveness of hair traps for surveying mammals: results of a study in sandstone caves in the Tasmanian southern midlands

We compared detection success of hair tubes and funnels with tape and Velcro adhesives as part of a small-scale mammal survey in sand-bottomed caves in the southern midlands of Tasmania. In order to detect small mammals entering traps but not leaving hair samples behind, a new type of funnel design was tested. In total, 19 species were detected throughout the survey period using a combination of hair traps and track and scat analysis. When tracks were observed inside funnel entrances no hairs were found on the adhesive tapes in 71% of cases. Hairs from several species were found in traps although there were no tracks of these species in the caves. These results further emphasise the importance of using multiple techniques when conducting general mammal surveys. Appropriate hair trap design is an important factor to be considered when conducting mammal surveys, as it has the potential to strongly influence survey efficiency and overall results.