Reintroducing and augmenting mountain goat populations in the north Cascades: Translocations from the Olympic Peninsula, 2018-2020

Harris, Richard; Rice, Clifford; Milner, Ruth; Happe, Patti

In response to a long-term decline in abundance of mountain goats (Oreamnos americanus) in many parts of their historic range within Washington’s Cascade Mountains, and taking advantage of Olympic National Park’s desire to remove non-native goats, the Washington Department of Fish and Wildlife led an effort to restore goat populations via reintroductions sourced from the Olympic Peninsula during 2018-2020. Following analyses that suggested where goats were most needed and would likely fair best, 326 goats (182 ., 144 .) were released at 17 sites (x¯ = 20.4 goats, minimum = 5, maximum = 49) over the course of 4 summer-time bouts; 262 were equipped with GPS collars allowing monitoring of survival and movements. Because most goats moved considerably after release, we found it useful to view them as having formed 6 population clusters (x¯ = 54.3 goats released/cluster). We analyzed adult (age 1+) survival and associated covariates at 3 temporal scales 1) 150 days, which we considered the acclimation period, 2) 150 days to 1 year, and 3) after 1 year. Overall annualized adult (age 1+) survival was 0.53 for females and 0.58 for males; survival was slightly lower during the initial acclimation period, but at ~ 0.8- 0.9 approached rates needed for population growth among those surviving a year in some population clusters. Adult females with higher body condition score survived better than those with lower scores. Kids were always abandoned by their mothers upon release, but at 0.25, estimated survival of orphans we monitored was higher than expected. The degree to which the translocation program succeeded in restoring inter-connected mountain goat populations in Washington’s Cascade mountains will not be known for a few more years.