Boreal forest titans do not clash: low overlap in winter habitat selection by moose (Alces americanus) and reintroduced bison (Bison bison)

Abstract

Despite moose (Alces americanus) likely being both an ecological and cultural keystone species in the North American boreal forest, few studies have examined niche overlap between moose and other ungulates. In response to concerns from local people about the potential for competition for habitat between moose and reintroduced bison (Bison bison), and the potential for disturbance to moose by bison and bison hunters, we investigated overlap in winter habitat selection by these species in southwestern Yukon, Canada. We used available geo-referenced data of animal locations, and associated environmental covariates, to develop resource selection probability function (RSPF) models of early-winter and late-winter habitat selection by moose and bison. In early-winter, moose selected sub-alpine shrub-dominated habitats, whereas bison extensively selected wet sedge meadows in lowland valleys. Both species used a greater variety of habitats in late-winter, with moose selecting drainages above tree line or river valleys with deciduous forest cover, while bison selected either south-facing grassy slopes or wet sedge meadows. Given observed differences in seasonal habitat selection between moose and bison, these species are predicted to overlap on only 0.5 and 6.6% of our 12,818-km2 study area during early-winter and late-winter, respectively. The lack of demonstrated winter habitat overlap between moose and reintroduced bison, coupled with low diet overlap, points to an overall low potential for competition for winter habitat between these species, or for disturbance to moose attributable to bison or bison hunters. Resource partitioning that facilitates coexistence on a shared landscape suggests that concern over the impact of reintroduced bison on resident populations of moose is likely unwarranted.