Modeling Viability of a Potential Canada Lynx Reintroduction to Isle Royale National Park

Abstract

Canada lynx (Lynx canadensis) were extirpated from Isle Royale in the 1930s. We conducted a population viability analysis (PVA) of a potential lynx reintroduction to better understand viability, uncertainty, and management options. We estimated that the 544-km2 island can support 30 lynx. The probability of 100-year population persistence was 0.36 for a model that simulated a decadal lynx-hare population cycle. A noncyclic model predicted a 0.73 probability of 100-year persistence. Inbreeding depression had a substantial negative effect on modeled persistence. Historically, periodic immigration of mainland lynx via an ice bridge probably reduced or prevented inbreeding depression on the island. The introduction of one male and one female lynx every 10 years increased the probability of 100-year persistence to 0.98 in the cyclic model. Occasional anthropogenic transfers of lynx to the island might be necessary because the frequency of ice bridge formation has decreased. However, our baseline models might underestimate viability because they used demographic rates from mainland studies where lynx were exposed to anthropogenic mortality. When we removed assumed anthropogenic mortality—which should be negligible on Isle Royale—the probability of 100-year persistence was 0.99 for the cyclic model, even without supplementation. Reintroducing lynx to Isle Royale appears feasible, assuming appropriate monitoring and management. Reintroducing lynx would restore a missing native species to Isle Royale and would increase our understanding of lynx ecology.