Five‐year assessment of wolf translocation to Isle Royale National Park, 2018–2023

Gray wolf ( Canis lupus ) translocation is a common approach for restoring ecological function through top‐down regulation. Understanding the processes that contribute to successful wolf translocations is essential for planning future restorations. We investigated the Isle Royale National Park (IRNP) wolf restoration project 5 years post‐translocation (September 24, 2018–September 1, 2023) to evaluate whether the management goal to establish a wolf population that would persist for 20 years was achieved. We used Global Positioning System (GPS) radio collar location data, remote cameras, howl surveys, and population viability analysis (PVA) to determine (1) if wolf demographics, including cause‐specific mortality, survival, pack formation, reproduction, and population size resembled long‐term averages and (2) whether observed wolf demographics would result in a self‐sustaining population for 20 years. The National Park Service released 19 wolves captured from populations in the Grand Portage Reservation, Minnesota, USA; the Upper Peninsula, Michigan, USA; Jostle Lake, Ontario, Canada; and Michipicoten Island, Ontario, Canada onto IRNP during September 2018–September 2019. The primary cause of wolf mortality was intraspecific aggression, with five of 11 confirmed mortalities attributed to other wolves. Average annual wolf survival was 0.74 (95% CI = 0.58–0.94), and across years the wolf population increased or remained stable with an estimated population of 27 wolves in April 2023. Wolves reproduced each year including the year of initial translocations. Population viability analysis simulations suggest an >80% chance of wolf population persistence for 20 years, despite high levels of inbreeding. We found that releasing socially bonded wolves facilitated pack formation; however, the numerical and social dominance of a family group may complicate the long‐term genetic health of the population.