Cascades fisher reintroduction project: Progress report for March 2017 to February 2018

Lewis, Jeffrey; Chestnut, Tara; Ransom, Jason; Werntz, David

Fishers (Pekania pennanti) were extirpated from Washington as a result of over-trapping, habitat loss, and predator eradication programs. A mid-sized member of the weasel family, fishers occurred in the coniferous forests of Washington until the early and mid-1900s. We established a partnership between federal, state, and non-profit organizations with the goal to restore fishers to their former range in Washington. This partnership reintroduced 90 fishers from British Columbia to Olympic National Park from 2008 to 2010, and we are now in the third year of a reintroduction project to restore fishers to Mount Rainier National Park (MORA), Gifford Pinchot National Forest (GPNF) and the larger South Cascade Ecosystem. In Year 1 of the project, we released 23 fishers (11 F, 12 M; each with a radio-transmitter) at a single release site on the GPNF. In Year 2, we released an additional 46 fishers (27 F, 19 M; each with a radio-transmitter), with 16 fishers released at one site in MORA and 30 released at one site in GPNF. As of February 2018, we have collected 776 locations of these fishers using aerial telemetry. The majority of the most recent locations of fishers (29 of 35 [83%]) occurred within the boundaries of the recovery area. These location data also indicated that 82% of Cohort 1 females, 42% of Cohort 1 males, 30% of Cohort 2 females and 42% of Cohort 2 males appear to have established a home range in their first year, and that 93% of these home ranges (28 of 30) were established within the recovery area. A 67% survival rate was estimated for Cohort 1 fisher during their second full year in Washington, and the same survival rate was estimated for Cohort 2 fishers during their first year (target objective >50%). Predation, vehicle collision, and injuries with secondary causes, were the most common causes when cause of death could be determined. We documented the first confirmed reproduction of fishers in the South Cascades in 2017, with female F023 photographed with one kit at her den tree. Because the large majority of females (23 of 38) were released as juveniles (10–11 months of age) it was unlikely that a large number of females would reproduce in Years 1 and 2 of the project. However, all surviving females (as many as 26) are now capable of giving birth in the spring of 2018. We could not release fishers in Year 3 due to extensive wildland fire impacts to the source population trapping area. We are now working closely with the government of Alberta, Canada, to begin trapping at a new source population, with intent to reintroduce fishers to the North Cascades beginning in the winter of 2018–2019. In years 4–6 of the project, we aim to release 80 fishers in the North Cascades and an additional 11 fishers in the South Cascades, with continued monitoring across both restoration areas.

Cascades fisher reintroduction project: Progress report for March 2017 to February 2018

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