The fortunes of fishers: on the wane in the West, the weasel's numbers are waxing in the East

Deborah Knight

The first two fishers Sally Beckwith raised for release to the wild were orphaned adolescents, and they took her to fisher school. They leapt horizontally between trees and stuck like Velcro balls. They chased each other headfirst down trees as if nothing were holding them, accelerating as they descended. When stressed or displeased, they emitted bloodcurdling screams.

Not long ago, Beckwith, a licensed wildlife rehabilitator who lives in Massachusetts, hadn't even known what a fisher was. The animals were eliminated from the state by the mid-1850s, and not until 1960 was another sighting recorded as they spread back southward from New Hampshire and Vermont. No one knows how many fishers now live in Massachusetts--they are rarely seen--but they do inhabit almost the entire state, even the suburbs of Boston.

Since her experience with those first fishers in 1996, Beckwith has raised one or two each summer, all of them orphans that would have died without her care. Each fall, as they learn to hunt for themselves, they leave home, vanishing from her backyard into the hundreds of acres of woods that surround her house. Beckwith's first love is orphaned river otters--also members of the weasel family--but fishers have come to take second place. The year she raised a lone fisher, a female, Beckwith was able to spend more rime with the animal and came to understand fully the similarities between the two species. "Fishers have a reputation of being ferocious," she says, "but I realized she wasn't ferocious. Her personality was similar to an otter's, but she was running around trees instead of water."

Fishers are among the least understood of the weasel family, or mustelids, which also includes martens, minks, ermines, ferrets, badgers, otters, and wolverines. They are so elusive that even researchers who study them in the wild rarely catch a glimpse lone except in a trap. They are primarily nocturnal, live only in forests with a dense canopy, and often rest during the day high up in trees. The males and females encounter each other briefly in the spring to mate, but the fertilized egg does not implant in the uterus until 10 or 11 months later. Then, after a 30-day pregnancy, the female gives birth to one to four tiny, hairless kits in a tree cavity, often an enlarged woodpecker nest. She cares for them until they can hunt for themselves at around five months of age. Other than that, fishers live solitary lives.

Perhaps the greatest mystery of fishers, though, is this: in the eastern United States and the Midwest, they are doing well and have retaken, either naturally or through reintroductions, much of their former range. In the West. however, they are doing so poorly that three times in the past decade groups have petitioned to have them listed as endangered.

In the West, fishers once ranged from British Columbia south through Washington, Oregon, and California to the southern Sierra Nevada mountains. Now they live in just three isolated populations. One of these, in the southern Sierra, is believed to be at high risk of disappearing. At best a few hundred animals remain, separated from the northern California population by hundreds of miles. Because they are a remnant of the original western fishers, they are genetically invaluable.

With so little known about the southern Sierra fishers, Mark Jordan, a graduate student at the University of California at Berkeley, has been trying to obtain basic information about them. Each summer he sets out 44 widely dispersed traps, which he and his assistants check regularly. They bait each trap with a chicken wing wrapped in a sock and tied inside a wire cage that snaps shut when an animal tugs on the sock. An attached wooden box provides the trapped fisher a place to hide.

Most often Jordan catches nothing. Luck was running with him one day last August, and he caught three. As he approached a trap, he heard a chuckling sound, the sign of a nervous fisher. Jordan shone a flashlight in the box's hole, and a dark little face with green eyes peered back. Later Jordan returned with two assistants. They unrolled a blue mat on the forest floor and laid out an assortment of equipment, including a syringe with anesthesia, a ruler, calipers, a scale, a tape measure, a thermometer, and antibiotic ointment. They injected the fisher, and after she h ad closed her eyes, they weighed her: just under five Founds. A male would have been half again as big or more. They laid her on the mat.

She already had an ear tag, since she had been caught the year before. This was her home range, probably about 10 square miles, which would not overlap with another female's range. Two of her four nipples were enlarged, a sign she had raised kits this year. She had told scars on her legs, body', and neck. Her nails were frayed, her powerful canines worn dull, her teeth covered with tartar, her gums red. She was mangy, with large patches of fur missing. Life, it seems, can be hard for a mid-sized forest carnivore, especially a female who must feed her young as well as herself. By contrast, field notes on a non-lactating female also caught that day reported an animal that "looked great": nothing but a few burrs on her fur.

When the sedated fisher's eyes opened, she was returned to the box. Later, when she had regained full control of her body, the box was opened. She shot out, scampered along the top of a 150-foot-long fallen tree as if on a highway through the woods, then bounded into the underbrush. Gone. This was the kind of place fishers like: a closed canopy, a supply of dead standing trees to make dens in, and plenty of trees of different heights and deadwood on the ground, where a hungry fisher might find prey. This forest was missing two items, though, that fishers commonly eat: snowshoe hares, which do not occur this far south, and porcupines, which once lived here but were killed off by humans. This fisher would have to make do with squirrels, voles, carrion deer, lizards, birds, insects, and fungi.

Fishers occur only in North America and once ranged from coast to coast throughout much of Canada and as far south as North Carolina and Missouri. By the early part of the 20th century, they were almost extinct in the United States. Unregulated trapping decimated their numbers, as the animals are relatively easy to trap, and they reproduce slowly. The females in particular were sought after for their fine, soft fur. In addition, logging and agriculture destroyed their habitat.

The decline of agriculture in the East has aided the fisher's regional comeback. Much of the land once cleared for farms has returned to forest, and the forests quickly produced a dense second growth. In these areas, fishers seem to manage with smaller trees for their dens and rest sites. In the West, the animals depend more on large, old trees and snags. This, combined with the animals' reluctance to cross open land, has led some scientists to conclude that recent clear-cutting of forests in the Pacific Northwest and forest fragmentation caused by extensive long-term logging in the Sierras may be preventing fishers from returning to their former range.

In 2000, environmental groups for the third time petitioned the U.S. Fish and Wildlife Service to list the fisher as an endangered species in Washington, Oregon, and California. The agency, however, has not acted. Reginald Barrett, a professor of wildlife ecology and management at the University of California, Berkeley, offers a reason: if the fisher were listed, it would stop both the National Forest Service and private timber owners from cutting forests they otherwise would cut. "Biologically, listing needs to be done," Barrett remarks. "Politically, it's not going to happen."

Fishers possess a talent unique in the world of predators: they regularly attack and kill porcupines. Their physical design suits them to the task. Since they are agile, quick, and low to the ground, they repeatedly dart in, bite the porcupine's face where there are no quills, and then retreat before the porcupine can swing its tail around. The porcupine may try to hide its face in the nook or a tree or climb, but the fisher can simply attack from above. Once the porcupine has been sufficiently wounded, the fisher flips it over and rips open the stomach, which is also free of quills. Afterwards, all that remains is an inverted skin. "Porcupines," says Barrett, "are pretty nice fatty packages."

The southern Sierra fishers once enjoyed these fatty packages. Porcupines, however, have another enemy: the timber industry. In winter, porcupines eat the inner bark of trees and can damage or deform them. Barrett reports there were widespread programs to eradicate porcupines in the southern Sierra. He has spoken with people who worked for the National Forest Service and the timber industry in the 1950s and 60s, putting out salt blocks laced with strychnine. The poisoning has stopped, but the porcupines apparently have not returned.

Fishers, in contrast, have elsewhere been popular with the timber industry and were reintroduced in several places in the United States and Canada in an effort to reduce porcupine numbers. In some areas, the plan did seem to work. Since the 1970s, Barrett has pushed for fishers to be transplanted into California's central Sierra mountains to restore the connection between the state's northern and southern populations, but in this case, he finds no support from the timber industry. "Now that there's talk of listing," he says, "they'd like the fisher to disappear."

Back East the comeback of fishers makes it likely that Sally Beckwith will continue to spend her summers acting as surrogate mother to fisher orphans. Since she allows her charges no other contact with humans, she has her hands full. The young ones love to play a game in which she tosses them 8 to 10 feet toward a tree, where they catch hold, then run back down for more. To give them practice catching prey, she swings a towel from her arm, and they attack it with a full tackle and bite. She uses eye contact and her voice to enforce strict limits on their behavior, as they would love to leap on her from a tree or tackle her legs and climb. She feeds them with care. Like other mustelids, fishers have a high metabolic rate and are ravenous eaters. "I have learned," she says, "never to get between any mustelid and its food."

Each animal has a personality. One summer she raised a male who was "a lummox, a slow-going, easy guy," and a female who was "like a coiled spring, an elastic band ready to fire." When the two played, the female dominated: if it was tag, he was always struggling after her; if it was an ambush, she was always the ambusher. Like all her young fishers, when awake, they were always on the move, and when asleep, the animals wouldn't wake even if you picked up a body part and dropped it. A cage in the woods serves as a den, and at first, Beckwith stays with her charges when they are out of their cage. As they get older, she leaves the door open. A day comes when they stay away overnight and are waiting for her in the morning, starving. Within days they learn to fend for themselves, faster than any other carnivores she has raised. They'll stay away two nights, then a week, then they are gone.

Beckwith spends her winters thinking about what they're doing, where they are. She muses, "I'd love to travel with a fisher."

Like most people, though, she has never seen one in the wild.

Deborah Knight is a contributing editor for Animals.

COPYRIGHT 2003 Massachusetts Society for the Prevention of Cruelty to Animals
COPYRIGHT 2003 Gale Group