Living amid the forested mountains and hills of Vermont and California is the rarely seen fisher (Martes pennanti), a member of the weasel family also known as the fisher cat or pekan in some parts. Keeping track of the fisher population is not simple because the animals are elusive and are spread out over wide areas.Wildlife researchers traditionally have used several techniques to catalog these and other hard-to-find carnivores such as bears and bobcats, including remote cameras and hair snares — devices that lure an animal close enough to snag a tuft of fur. But it turns out that the best way to survey forest beasts is to send in the dogs.Investigators from the US Geological Survey Vermont Cooperative Fish and Wildlife Research Unit at the University of Vermont in Burlington and from the US Department of Agriculture Forest Service’s Pacific Southwest Research Station in Arcata, Calif., compared how well cameras and hair snares stacked up with dogs trained to detect the scat left behind by black bears, bobcats and fishers. Every two weeks they brought the dogs to sites throughout Vermont to search for scat. At some of these sites, they set up infrared sensors made by Goodson & Associates Inc. of Lenexa, Kan., that triggered Yashica or Canon film cameras. In the next set of trials, they used combined camera/sensor devices made by CamTrak South Inc. of Watkinsville, Ga. Collocated with the cameras were hair snares, placed by the researchers.Over time, they found that the dogs were the best — and the most cost-effective — way to detect the presence of all three species. Importantly, the dogs generally required only one visit to a site to complete their task, whereas cameras and snares had to be visited repeatedly to increase the likelihood of getting a positive sighting.Dogs are now being used in similar applications elsewhere, including in a survey of the endangered Pacific fishers (Martes pennanti pacifica) within the Sierra National Forest in California.