Human-caused mortality triggers pack instability in gray wolves

Kira Cassidy

Research Associate, Yellowstone Wolf Project

Abstract

Transboundary wildlife movements result in some of the most complicated, unresolved wildlife management issues across the globe. Depending on location and managing agency, gray wolf (Canis lupus) management in the United States ranges from preservation to limited hunting to population reduction. Where most wildlife studies focus on population size and growth rate to inform management, relatively few examine species biological processes at scales different from the population. This is especially important for group-living species such as the gray wolf where the breeding unit is the social group. Our study used data on gray wolves living primarily within several National Park Service units (years of data): Denali National Park and Preserve (33 years), Grand Teton National Park (23 years), Voyageurs National Park (12 years), Yellowstone National Park (27 years), and Yukon-Charley Rivers National Preserve (23 years). We identified two gray wolf biological processes different from population size: pack persistence and reproduction and determined that while anthropogenic mortality had negative effects on both, pack size had a moderating effect on the impacts of mortality.