Trail-based outdoor recreation, including dog-walking, jogging, and bicycling, is on an upward trend, especially near cities. Noting that the mere presence of humans can disturb wildlife, researchers in Sweden wondered whether the change of vegetation and fragmentation of habitat caused by creation of trails, or the presence of humans on the trails was more disruptive to wildlife.
They looked at trails in four forests with similar habitats, two of which were heavily used for recreation, and two with little visitation. They assessed bird density at 50 and 120 meters from the trails. On trails with heavy use, areas farther away had much richer birdlife than those close to the trails, but no such difference was detected on trails with little usage. They found more bird nests far from heavily used trails than near them, and found no such difference along little-used trails. They found that the disturbance caused by recreation activities reduced forest bird density by 13 percent and species richness by 4 percent. This effect was not merely due to the habitat modification associated with the presence of trails. Habituation to humans was not evident on the well-used trails.
The researchers conclude that trails affect wildlife primarily by increasing human activity in wildlife habitat, and less so by disturbing the ecosystem.
Read the full report here: https://www.frontiersin.org/articles/10.3389/fevo.2018.00175/full
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