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Abstract:
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"In their recent article, Whittington et al. (2004) show that wolf packs increase their path sinuosity in the vicinity of roads and highly used trails. This path variable is defined as the relationship between the length of the path traveled (L) and the net displacement of the animal (R). The authors present a model that explains path sinuosity using the distance to prey and the density of roads and trails. Such studies demonstrate the potential impact of human developments on wild animals. However, wildlife management often requires assessing whether a proposed human activity presents a significant risk for a species. Assessing long-term risks is difficult in studies that occur over brief ecological time scales. The type of response variables collected by Whittington et al. (2004) can help to relate the short-term effects of anthropogenic activities to their long-term consequences. Path sinuosity can be related to an individual's cost of transport, i.e., the amount of energy the individual needs to travel a given distance. This in turn can be related to road and trail density thanks to Whittington et al.'s model. This forecasting model can then be used to assess the added cost of transport (in kcal • kg-1 • km-1) for each individual wolf in terms of roads and trails. This value can then be extrapolated for the two packs (13 individuals), and the added energetic cost to the ecosystem, i.e., the amount of energy wolves need to consume to meet the added cost of transport, can be balanced with the known amount of energy, i.e., prey, available. This approach greatly simplifies reality, but it can help approximate the cost of road and trail construction at a population level."
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