Red deer (Cervus elaphus) avoid mountain biking trails

Human outdoor activities commonly affect animal behaviour. Ungulates often avoid roads and trails and increase their avoidance with expanding and intensifying human recreational activity. Recently, mountain biking has become increasingly popular in many regions in Norway, but we still have limited knowledge about how mountain biking may affect wildlife. In this study, we used pellet-group counts and camera traps to study the effect of mountain biking on red deer abundance in Kaupanger, Norway. Pellet-group counts decreased close to biking trails, and it appeared that red deer avoided using areas within 40 m of such trails. Camera trap data showed that there was a tendency for deer abundance to decrease with increasing human activity (trail width) during daytime. Males reacted more strongly to this increasing activity than did females. Even with a small-scale approach, focusing on within-stand effects, we found that red deer were affected by mountain bikers and avoided areas close to biking trails. Our findings imply that any further increase in mountain biking may result in greater avoidance and, thus, less suitable habitat for red deer in forest areas.