Joggers cause greater avian disturbance than walkers

Human recreational activities are increasing in natural areas where they potentially disturb the normal activities of wildlife. Prolonged disturbance can be detrimental to animals and may ultimately lead to decreasing wildlife populations in highly disturbed areas. However, little is known regarding how wildlife assesses the risk of human-related activities and whether escape responses are accordingly modulated. For example, although walking is the most common pastime in many natural areas, jogging is becoming increasingly common. Joggers move faster than walkers and may therefore be perceived by wildlife as a greater threat. However, this concept has rarely been tested. In addition, the specifics of how joggers and walkers are visually and acoustically perceived by wildlife are unknown. We predict: 1) that joggers loom more rapidly in the animal's field of view than walkers, and they also create more noise, especially on certain substrates; and, 2) that joggers will evoke escape responses at longer distances and/or of greater intensity than walkers. We demonstrate that joggers loom more rapidly, and they also create more noise, especially on gravel surfaces. For eight of the ten bird species tested, individuals fled earlier and/or displayed more intense escape responses (e.g. flying instead of walking away) to joggers than walkers. These findings suggest that land managers should not only regulate the type of stimulus that may disturb wildlife, but also the speed at which they move through the environment. Activities such as jogging, which are generally regarded as low impact, may create more wildlife disturbance than previously thought.