Impacts of vehicle traffic on the distribution and behaviour of rutting elk, Cervus elaphus

Even within protected areas, human disturbance has the potential to influence the distribution, behaviour and, ultimately, abundance of other species. We studied the potential disturbance caused by the presence and movement of vehicle traffic on the distribution and behaviour of elk (Cervus elaphus) during the fall rut in a Canadian National Park where people congregate on a single road to observe elk. To determine the effect of vehicle traffic on elk, we subjected the road to alternating open and closed treatments of 3 or 4 days in duration. We then used a global positioning system (GPS)-linked laser range finder and a computer programmed as an event recorder to collect information on the distribution and behaviour of elk. These methods made it possible to link the precise positions of both elk and vehicles with behavioural states, which we measured with a combination of focal animal, all-occurrence, and scan sampling. We detected no effects of road closure on the distribution of elk herds or the size, cohesion, or position of separate elk groups, but elk were more likely to cross the road when it was closed. In addition, higher proportions of female elk were vigilant in the vicinity of moving vehicles and elk of both sexes, but particularly males, spent more time in vigilance postures when the road was open. Males spent less time exhibiting reproductive behaviour (sparring and mating) when the road was open and tended to spar farther from the road. Together, these results suggest that vehicle traffic exerted a measurable effect on the behaviour, but not distribution, of elk at this site. These behavioural effects are probably biologically slight, but they could easily be lessened at this site, and potentially others, by limiting the frequency and extent of vehicle movement on the road.