Herbivores must balance energy needs with avoiding risks, using various cues to assess predation risk. The American beaver (Castor canadensis) is a semi-aquatic herbivore vulnerable to predation on land by wolves (Canis lupis). We tested the use of wolf urine as a potential tool to reduce human–beaver conflicts. We used infrared cameras to monitor use of terrestrial foraging trails by beavers during food cache construction in Seney National Wildlife Refuge, Michigan, from September to November 2008. Two foraging trails at 15 colonies (30 total trails) were monitored for 1 week to establish baseline use. One trail from each colony was then treated with wolf urine, and all trails were monitored an additional week to estimate changes in trail use. Mean number of beavers detected decreased 95% on urinetreated trails and was unchanged on untreated trails. Beavers also spent 95% less time on urine-treated trails as estimated by photograph time stamps, but did not change time spent on untreated trails. Sixteen other taxa of wildlife were detected; however, avoidance of urine-treated trails was not observed in these taxa. Species richness increased with urine treatment, mostly due to increased visitation by carnivores. Beavers appear to use olfaction to assess predation risk on land. Wolf urine may be a suitable deterrent for beaver herbivory.

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