Conservation and Trapping News

Fishers are returning to Washington State forests
Oct 9, 2022 06:05 ET

[Reprinted from original]

Jeff Lewis sped through an evergreen forest in the Cascade Mountains, southeast of Seattle, hearing a faint “beep” from a radio transmitter implanted in an animal code-named F023.

F023 is a fisher (Pekania pennanti), an elusive member of the weasel family that Lewis fondly refers to as a "tree wolverine." Despite fur trapping and habitat loss, Washington's population remained subdued by the mid-1900s.

Lewis started tracking F023's radio signal from a plane two or three times a month, along with dozens of other recently released fishers, in the spring.

Lewis, a conservation biologist with the Washington Department of Fish and Wildlife, examined her surroundings for signs that she might be "busy with babies." If yes, she would be the first wild-born fisher documented in the Cascades in at least half a century.

The researchers discovered a clump of fur snagged on a branch, scratch marks on the bark of a pine branch, and — the best clue of all — fisher scat. A few days later, after looking through thousands of photos of squirrels and deer, the group found a grainy photo of F023 ferrying a kit down from her den high in a hemlock tree.

"When it comes to getting photos like that, we're all just a bunch of little kids," Lewis adds.

This remarkable development was brought in during the second phase of a 14-year fisher reintroduction effort. From 2008 to 2010, the project shifted its focus east of Seattle, moving 81 fishers in the South Cascades (home to Mount Rainier National Park) from 2015 to 2020, and then 89 fishers in the North Cascades from 2018 to 2020. The animals were brought from British Columbia and Alberta.

The fisher recovery efforts in Washington relocated the animals to three areas of the state: the Olympic Peninsula west of Seattle and the North and South Cascades, a mountain range separated by Interstate 90.

Biologists set out to record newborn kittens as an indicator of how fishers performed in the three relocation areas as part of Washington's Fisher Recovery Plan.

Biologists had already confirmed the births of seven relocated females on the Olympic Peninsula, where the whole project began. Two of the seven females had four kits, the largest litter size ever documented on the West Coast, according to Patti Happe, the wildlife branch head at Olympic National Park.

Lewis is often asked why put all of this effort into restoring a species many people have never heard of? Lewis' answer: A wide array of carnivores makes the ecosystem stronger.

Happe explains to another motive: "They're freaking adorable — that's partly why we're saving them."

Fishers don't hunt fish, although they'll happily devour a dead one if it's handy. Males can weigh up to six kilograms, about twice the amount of females. They also can climb up to two meters between branches in a day.

Fishers' stubby legs and exceptional climbing abilities make them a threat to tree-climbing porcupines. It's not pretty: A fisher will drop the quill-covered animal down a tree and assault its face until it dies of blood loss or shock. Then the fisher skins the vulnerable animal, eating most of it except the quills and bones.

In the 1800s, trappers began hunting fishers for their fur. Soft and luxurious, the glossy brown-gold pelts were sought after fashion accessories, selling for as much as $345 each in the 1920s. porcupines spread throughout the Great Lakes region and New England, wreaking havoc on forests.

Private timber companies partnered with state agencies to reintroduce fishers to several states in the 1950s and 1960s, enabling fishers to flourish again in Michigan, Wisconsin, New York, and Massachusetts.

However, fisher numbers in Washington, like in most of the West, were still small. At the turn of the 21st century, no fisher had been seen in the state for more than three decades.

Private timber companies in Washington encouraged the return of fishers. Mountain beavers — a large, primitive rodent endemic to the Pacific Northwest — play a similar role in Washington's evergreen forests. They eat tree seedlings. And fishers eat them.

The state of Vermont had devised a strategy to bring the animals into Canada in 2006, according to Lewis. "It was a great opportunity to restore a species."

F023's relocation story began when she entered a box trap in British Columbia, lured by a tasty morsel of meat. Conservation Northwest is one of the project's three main partners, along with Washington Fish and Wildlife and the National Park Service. F023 received a surgically implanted radio transmitter and was driven across the border.

F023 was released just south of Mount Rainier National Park by members of the fisher recovery team, which gathered around the tree's perimeter in an effort to involve the general public in promoting fisher recovery. Everyone froze as a child opened the door, and the furry female bounded into the snowy woods, out of sight in a flash.

For up to two years, the team monitored each relocated fisher to see if the project met key expectations of success in each of the three regions: more than 50 percent of fishers survived their first year, at least half established a new location near the release site, and a confirmed kit born to at least one female.

"We achieved those milestones," says Conservation Northwest's science and conservation director Dave Werntz.

A series of bypasses constructed over and under Interstate 90 east of Seattle may have aided the process. One of these structures is the largest wildlife bridge in North America, an overpass that is "paved" with forest. In 2020, a remote camera captured an image of a fisherman moving over one of the underpasses.

"Male fishers go on these huge walkabouts to seek for females," Werntz says. While biologists assumed fishers would cross the freeway to look for mates, having photographic proof "is pretty amazing," he says.

Happe and others expect to see wildlife crossings along Interstate 5 one day. According to Happe, the Olympic and Cascade populations are at odds with the freeway, which runs north-south near the coast.

According to radio tracking, the majority of the initial 90 fishers who came to the Olympic Peninsula settled well into their new homes. In the year following their release in that location, the fisher survival rate averaged 73%, but varied depending on the year and season they were released, as well as the gender and age of the fishers.

Males performed better than females, partly due to their smaller bodies and less vulnerable to predators, such as bobcats and coyotes, as reported in the April 2022 Journal of Wildlife Management.

Because the first fishers to the Olympic Peninsula were released in different areas, the animals had difficulties finding mates. As a result, only a few parents sired the subsequent generations.

Six years after moving to the Olympic Peninsula, Happe and colleagues built 788 remote cameras and hair-snare stations: triangular cubbies open on either end with a chicken leg as bait in the middle, and wire brushes protruding from either side to grab strands of fur. DNA analysis of the fur raised suspicions of inbreeding.

"Models predicted that we'd lose up to 50 percent of genetic diversity, and the population would thrash out in about 100 years," Happe adds. In 2021, the team brought 20 more fishers to the Olympic Peninsula, while the original population had hailed from British Columbia.

The team adapted following the lessons learned from the Olympic Peninsula. For instance, to increase the likelihood of fishers finding each other more quickly, the animals were released at smaller sites closer together in January, giving females plenty of time to settle into a home range before the spring mating and birthing season.

More unanticipated findings emerged as the experiment went on. Fishers who relocated north of I-90 were more likely to survive the first year (776 percent) than those who relocated north of I-90 (40 percent), according to Tanner Humphries, the lead program leader for Conservation Northwest.

Fishermen are now using different habitat types than biologists predicted, according to Happe. Large, old trees with cavities for denning and resting are being utilized by fishermen in younger managed forests, where prey may be easier to find.

Fishers' preferred prey — snowshoe hares and mountain beavers — were most abundant in early regenerating forests, according to Mitchell Parsons, a wildlife ecologist at Utah State University in Logan, who reported with Lewis, Werntz, and others in 2020 in Forest Ecology and Management.

The mother's tracking chip failed as intended after the baby was caught on video five years ago — the component lasts only two years. Since then, many more fisher kits have been born in Washington.

These carnivores are one of the most successfully translocated mammals in North America. According to Lewis, 41 different translocation campaigns have helped fisher populations thrive. The animals now occupy 68 percent of their historical range, up from 43 percent in the mid-1900s.

The relocation phase of the project, which began in 2021, has come to an end. Lewis, Happe, and their partners intend to keep monitoring how these graceful tree-climbing carnivores are doing — and how the ecosystem is responding. For instance, fishers are actually eating seedling-eating mountain beavers, according to Happe, Lewis, and others in 2021 in Northwestern Naturalist.

Animals around the world are facing significant challenges as a result of climate change, habitat loss, and ecosystem degradation. Lewis believes that the fact that fishers are flourishing once again in Washington gives hope.

"It's a difficult time, it's a tough world, and this feels like something we're doing right," he says. "We're regaining it instead of losing it."