Movements, connectivity, and resource selection of Rocky Mountain bighorn sheep

Species that exist in naturally fragmented subpopulations can maintain long-term viability through interpopulation connectivity and recolonization of suitable habitat. We used radiotelemetry to study movements of 3 herds of bighorn sheep (Ovis canadensis) that recently colonized previously unoccupied parts of western Montana. These herds also provided a unique opportunity to compare resource-selection patterns in newly colonized habitats, and we used logistic regression in a global information system framework to generate predictive models for females in each herd. We detected relatively long (19- to 33-km) extra-home range movements by males in all 3 herds, and connectivity with nearby bighorn and domestic sheep herds. An information-theoretic approach to model selection revealed greater differences in resource selection among herds than anticipated. Initial evaluation of resource-selection models by resubstituting data showed excellent predictive accuracy (P <= 0.002), but testing models across sites gave mixed results, and in many cases, poor fit (0.001 <= P <= 0.960). High vagility of males and variability in resource selection by females suggests increased potential for future recolonization and connectivity.