| This study addresses concerns among park managers at Voyageurs National Park, Minnesota, that killing of gray wolves (Canis lupus) near the park may combine with changing prey density, diseases, disturbance, and other environmental factors to threaten the park's wolves. My purpose was to provide insights about wolf management by projecting population trends under different cumulative effects scenarios. I used a stochastic, spatially-structured, demographic simulation model to investigate (1) how human-caused mortality combines with regional environmental conditions to affect wolves inside the park, and (2) how much disturbance it takes to change the park wolf population. The study includes extensive model sensitivity analysis and synthesis of literature and expert knowledge on wolf demography.;In the first experiments, I considered four factors that are most likely to impact wolf population size---prey density, human-caused mortality, immigration and disease mortality---and how they combine and accumulate to affect the risk of population decline. The level of pup disease or mortality most strongly influenced whether the park core wolf population declined from high levels. However, the number of immigrating wolves largely determined whether or not the population fell below six wolves or was extirpated. Prey biomass had minimal impact on the park core population unless it determined average territory sizes and hence, the number of wolf territories that could fit within the park core. Human-caused mortality did not affect the number of park wolves, provided wolves in the two or three park core territories were protected. The simulations also indicated that the park is a net source of emigrating wolves, yet simultaneously immigrants are a routine part of the breeding population under all conditions and essential to preventing extirpation under severe conditions.;In the second experiments, I determined how frequently individual wolves, litters of pups, and packs had to be disturbed---lost or displaced from their territories---to cause measurable impacts to the park core population. The results can assist field researchers in establishing whether or not human disturbance is affecting the wolf population. I conclude by summarizing possible threats to wolves at Voyageurs and recommending management priorities. |
