Cooperative Fish and Wildlife Research Units Program: Alaska
Education, Research and Technical Assistance for Managing Our Natural Resources

Livelihood systems that depend on mobile resources must constantly adapt to change. For people living in settled communities, environmental changes that affect the distribution of a migratory species may reduce the availability of a primary food source, with the potential to destabilize the regional social-ecological system. North American indigenous communities harvesting arctic caribou represent a social-ecological system for which food security depends on movement patterns of a migratory resource. Quantitative assessments of physical, ecological, and human effects on caribou distribution have proven difficult because of the significant inter-annual variability in seasonal caribou movement patterns. We developed and evaluated a modeling approach for simulating the distribution of a migratory herd throughout its annual cycle over a multi-year period. Beginning with previously defined spatial and temporal scales for the model, we used satellite collar locations for the Porcupine Caribou Herd (Rangifer tarandus granti) to compute and analyze the season-by-season probabilities of movement between habitat zones under two alternative climatic conditions for each season. Using these contingent movement probability tables, we simulated the sequence of caribou movements across the landscape in response to externally-imposed climate drivers. Statistical tests of predicted seasonal caribou distribution showed that the predicted distributions were consistent with observed of distribution, and significantly correlated with subsistence harvest levels for three user communities. Our approach could be applied to other caribou herds and could be adapted for simulating the distribution of other ungulates and species with similarly large inter-annual variability in the use of their range.