SEASONAL MOVEMENT, SPACE USE, AND MORTALITY OF GRAY WOLVES, MOOSE, AND WHITE-TAILED DEER IN NORTHEASTERN MINNESOTA

BackgroundThe Anishinaabe people of the Grand Portage Band of Lake Superior Chippewa manage for subsistence moose (mooz; Alces alces) and white-tailed deer (waawaashkeshi; Odocoileus virginianus) harvests and conservation of gray wolves (ma’iingan; Canis lupus) within the 1854 Ceded Territory in northeastern Minnesota, USA. Prey, such as moose and deer, vulnerability varies seasonally. Predators, such as wolves, may respond to increased prey vulnerability by shifting their space use to match prey via migratory coupling and ecological seasonality. MethodsWe assessed seasonal space use of gray wolves, moose, and white-tailed deer as well as seasonal mortality of moose and deer on and around GPIR. We analyzed GPS collar data collected by the Grand Portage Band and the National Park Service during 2008–2022. We used Brownian bridge movement models in Migration Mapper to estimate individual- and population-level occurrence distributions and determine the status and timing of range shifts; we estimated the proportion of wolf utilization distributions overlapping moose and deer occurrence distributions. We used cluster and principal component analyses to estimate timing and drivers of seasonal changes in space use among populations, and we used weighted autocorrelated kernel density estimation for weighted resource selection functions to assess seasonal habitat selection for each population. Finally, we estimated mortality timing using time-to-event models informed by weather data and population-level species space use. ResultsOur analyses identified a single migration corridor through which white-tailed deer synchronously departed GPIR. Gray wolf utilization distributions overlapped the deer migration corridor similarly across seasons, but wolves altered within-range space use seasonally in response to prey distributions. Seasonal space use shifts by wolves resulted in greater overlap with deer during fall migration and greater overlap with moose during summer. Space use shifts followed a two-season pattern with transitions between seasons coinciding with changing weather and deer migration. Moose mortality peaked during pre-parturition transitions between seasons and during the summer–winter transition. Deer mortality peaked during spring migration in late winter and during fall migration in late summer.ConclusionsGray wolves did not increase their use of the white-tailed deer migration corridor but shifted spatially within their territories in response to seasonal variations in prey distributions. Seasonal space use among all populations was likely due to deer migration. Our findings suggest ecological seasonality of predators is linked to prey via seasonal space use dynamics but was not associated with parturition. Our results indicate mortality timing coincided with transitions between seasonal space use states suggesting ungulates are at greater mortality risk during these periods. Our results can be used to improve management including sampling schedules, population modeling, and harvest regulations on GPIR under Anishinaabe principles of seventh-generation conservation.