Stalking the Elusive Fisher
Finally, the existence of this rare
predator is confirmed.

By Steve Gehman From Yellowstone Science, Fall 1995

It was mid-February 1985. My friend Michael Osgood and I had spent three days skiing from West Yellowstone to Shoshone Lake, and were just settling into our sleeping bags inside the quinzhee that we built for shelter within a mile or so of the Shoshone Geyser Basin. In the early evening darkness we heard a clanging of pots from our snowshelf kitchen outside. We slid out of our bags, down the entrance tunnel, and out into the darkness with flashlights clenched between our teeth, to see a medium sized, dark animal bounding away with a two-pound block of cheese from our food bags.

As we shouted and moved toward the animal, it dropped the cheese and disappeared into the nearby forest. We retrieved the cheese and the remainder of our food and cooking equipment and returned to the comfort of our snowhouse. Within a few minutes, as we sat discussing our encounter and wondering about what we had just seen (it seemed too large and too dark to be an American marten), the animal came bounding into our quinzhee and perched itself at the base of the sleeping platorm. From less than siz feet away, illuminated by flashlights, we saw the dark brown fur, long bushy tail, and red eyeshine of a fisher. We sat motionless and stared at this creature, mesmerized by its boldness and beauty. After five or ten seconds, the fisher turned and disappeared into the darkness from whence it came. So began my interest in fishers in the Yellowstone Ecosystem.

During the winter of 1992-93, I had the opportunity to become involved in the Northern Yellowstone Carnivore study, a cooperative project between Yellowstone National Park and Yellowstone Ecosystem Studies (YES). The effort was initiated by Sue Consolo Murphy of the National Park Service (NPS), Mary Harter (NPS) and Bob Crabtree (YES) in an effort to expand our knowledge of medium-size mammalian carnivores in the northern portion of Yellowstone. The objectives of the study are to evaluate various inventory and monitoring techniques for carnivores, to determine presence and distributions of carnivores, and to assess habitat relations of the various species. Although we are interested in all carnivores, our primary target species include some of the lesser studied animals such as American marten, fisher, wolverine, lynx and mountain fox.

Over the past three winters, numerous people have participated in operating remote camera stations, maintaining hair snaring devices, and conducting snow track transects in efforts designed to learn more about these animals. Mary Harter and Sue Consolo Murphy developed and implemented field techniques for the study in the winter of 1992-93, with assistance from YES personnel Rob Ahl, Ammy Gillesberg, and me. During the past two winters, I have served as project leader for YES, and have received help in the field from numerous student volunteers, interns and YES staff. In particular, interns Rob Ahl and Betsy Robinson deserve special acknowledgement for contributions of time and energy to the project. During each of the three winters of study, we have also received field assistance and support from YES "research volunteers" (approximately 25 individuals) who volunteered a week or more of their time participating in YES's "Searching for Carnivores" research program.

One highlight of the study occurred this past winter, when fishers were captured on film at two of our remote camera stations in the Cooke City area. The first fisher photo was taken on the morning of January 9, 1995, in the Republic Creek drainage south of Cooke City. We had been tantalized by the prospect of fisher presence in the area since early in 1993, when a photo from one of our first camera stations showed us the rump and tail of a nearly black mustelid digging in the snow and facing away from the camera. Bob Crabtree and I suspected it to be a fisher, but could only cautiously label it as a "possible" fisher in our project reports and discussions.

During the remainder of that first winter and throughout the second winter of study, we worked hard to confirm what we suspected, but came up only with a few sets of probable fisher tracks (there is potential for overlap in track size between marten and fisher, so confirmation of fisher presence from tracks alone is questionable). Needless to say, we were quite excited to see the unobstructed profile of a fisher on our film from the Republic Creek site. In late February 1995, a second fisher was photographed at a camera station along the northeast boundary of Yellowstone National Park, at Wolverine Pass (approximately 6 miles northwest of the Republic Creek site). This photo was of a lesser quality than the one from Republic Creek, but nevertheless provided a conclusive view of a fisher.

These photos leave no doubts in our minds that fishers occur in the northeastern portion of the Yellowstone Ecosystem. The dark brown color of the animals, the lack of any orange coloration showing along the edges of the neck, chest or belly (a typical pattern in martens, the most likely alternative animal), the large bushy tail; the relatively blunt, rounded shape and low profile of the ears; and the relatively robust appearance and large size of the body, all support our conclusion that the animals in the photos are fishers and not martens.

To confirm our identifications of these animals as fishers, Betsy Robinson and I made estimates of the body and tail lengths of the animals by careful scrutiny of the photographs and the camera sites. We revisited both camera sites and made numerous measurements of the areas photographed and of vegetation included in the photos. We also took photographs of rulers and an 18 X 18-inch grid placed in the locations of the photographed animals. These photos were then used to compute correction factors that were applied in estimating the actual sizes of the animals from measurements of the animals on the original photos. Resultant estimates indicated that the animals' bodies and tails were within normal ranges for fishers, and were larger than comparable measurements for marten.

After a century of both speculation and doubt about the presence of fisher in the Yellowstone Ecosystem, we are extremely pleased with these confirmations. These recent sightings, probable tracks in classic fisher habitat, historical sightings, and two fisher specimens from unknown locations in the Yellowstone region all point to a probably historic population.

This information raises some fascinating questions. For example, how could a 5- to 10-pound predator go unnoticed for so long? How well distributed are they? Do fisher have a thriving, viable population in Yellowstone or are they isolated and threatened? One thing is for sure. There is no substitute for partnerships: pooling our resources and getting out in the field and looking. What else could be waiting for us to discover? We hope we can expand our efforts to learn more about distributions, abundance, and habitat use of these elusive carnivores.

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