COS 56-3 - Diagnosing habitat quality with reintroductions: A case study with fishers on a landscape managed for timber production

Tuesday, August 8, 2017: 2:10 PM
B110-111, Oregon Convention Center


Aaron N. Facka, Oregon State University; Sean M. Matthews, Oregon State University; Roger A. Powell, North Carolina State University; Richard Callas, California Department of Fish and Wildlife; Deana Clifford, California Departement of Fish and Wildlife; J Scott Yaeger, U.S. Fish and Wildlife Service; Tom Engstrom, Sierra Pacific Industries; Ed Murphy, Sierra Pacific Industries; Laura Finley, United States Fish and Wildlife Service; Kevin P. Smith, North Carolina State University; Pete Figura, California Departement of Fish and Wildlife


Intentional translocations of animals should ideally occur in places with the best possible habitat that leads to high rates of population growth and long-term persistence of populations. Because humans have affected natural systems dramatically, few places may exist that have optimal or unaltered habitat. Additionally, researchers and managers may not know the true habitat quality of a location. Experimentally reintroducing organisms into locations with possibly acceptable, but unknown, habitat quality is one approach that may elucidate habitat quality and provides information that is applicable for research and conservation. The fisher is a species of concern in much of western North America due in part to the perceived inability of fishers to live on landscapes logged commercially. From 2009 to 2011, we reintroduced 40 fishers (24F:16M) onto an industrial timber landscape. We estimated the survival, reproduction and habitat associations of these initial founders and their progeny through 2015 to understand if the land management methods and landscape could support establishment of a new fisher population. Additionally, we constructed a stochastic matrix population model based on the observed vital rates to evaluate how likely the population was to go extinct under current conditions.


Through 6 years after release, and concurrent with active logging operations, >90% of all locations of fishers were on or within 2 km of the study site. Fishers selected stands of dense trees with high canopy cover, large average tree diameter, and moderate numbers of hardwood trees whereas they avoided clear-cuts or young stands of regenerating trees. Female and male fishers had high monthly survival (>0.95), and we documented that on average 79% of adult females gave birth with an average litter size of 1.7 ± 0.41. Mean rates of survival and reproduction were constant across years and all vital rates were similar to populations of fishers elsewhere in California. By 2014, population processes, in particular reproduction, was independent of the founding fishers. After 6 years, the population consisted mostly of young fishers born on the study site. Estimates of populations size indicated a relatively small (minimum number alive = 70 fishers) but increasing population of fishers. Stochastic population simulations suggest that the population is unlikely to go extinct within the first 10 years after moving fishers. We conclude that logged landscapes offer opportunities to establish and manage populations of fishers at similar levels of logging intensity observed on our study site.