Ausband, D.E., S.J. Thompson, B.A. Oates, S.B. Roberts, M.A. Hurley, and M.A. Mumma. 2023. Examining dynamic occupancy of gray wolves in Idaho after a decade of managed harvest. Journal of Wildlife Management. e22453.
Abstract
Gray wolves (Canis lupus) were reintroduced to Idaho, USA, in 1995–1996. The removal of Endangered Species Act protections in 2011 transferred wolf management to the state where wolves were subsequently classified as a harvested (i.e., hunted and trapped) big game species. We implemented a camera-based survey across Idaho from 2016–2021 as part of a population monitoring program and used the resulting camera trap images in a multi-year, dynamic occupancy model to assess influences on wolf distribution. Our objective was to understand how habitat, prey, humans, harvest, and livestock and prey-related wolf removals affected wolf occupancy, as well as colonization and extinction of areas between years. Wolf occupancy did not change appreciably over the course of our study, with an estimated high of 0.44 (SE = 0.03) in 2018 and a low of 0.39 (SE = 0.03) in 2020. Wolf colonization (i.e., probability that a cell switched from unoccupied to occupied between years) was positively associated with forest cover, images of humans, and percent of neighboring cells that were occupied. Cell extinction (i.e., probability of switching from occupied to unoccupied between years) was negatively associated with neighboring cell occupancy. There was a non-linear relationship between wolf harvest and both colonization and extinction. Wolf harvest often occurs in areas where wolves are abundant or in areas of repeat conflict (e.g., areas where recolonizing wolves are repeatedly removed due to conflicts with livestock). Thus, harvest is linked with local wolf abundance at lower levels of mortality, but higher levels of mortality reduce the probability of colonization while increasing the probability of local extinction. Our results indicate that although harvest might influence wolf occupancy at local scales, wolves remained widely distributed throughout Idaho after more than a decade of harvest.