Measuring the cost of risk avoidance in brown bears: further evidence of positive impacts of ecotourism.

摘要

The objective of this study was to determine the cost to female brown bears with cubs of avoiding risk, or perceived risk, from both large adult male bears and ecotourists. We measured salmon consumption by brown bears in British Columbia under different risk scenarios (the presence and absence of large male bears and people). Declines occurred despite superabundant food where consumption was never limited by salmon abundance. While there were significant changes in the proportion of time spent foraging and in the consumption of captured fish between periods with and without ecotourists present, there was no change in foraging effectiveness, catch per unit effort. Selection of sub-optimal habitats to reduce predation risk incurs energy costs. Risk avoidance reduced daily salmon consumption by females with cubs by more than one third. By associating with people, females with cubs were able to avoid encounters with large, potentially aggressive males, which avoided people in both time and space. Controlled human activity at feeding sites can provide a temporal feeding refuge for vulnerable age/sex classes. This is the first study to quantify the energetic cost of intra-specific risk-avoidance for a large carnivore.