Seasonal Climate Variation and Caribou Availability: Modeling Sequential Movement Using Satellite-Relocation Data

Craig Nicolson, Department of Natural Resources Conservation, University of Massachusetts, Amherst
Matthew Berman, Institute of Social and Economic Research, University of Alaska Anchorage
Colin Thor West, Department of Anthropology, University of North Carolina at Chapel Hill
Gary P. Kofinas, Department of Humans and Environment and Institute of Arctic Biology, University of Alaska, Fairbanks
Brad Griffith, U.S. Geological Survey Alaska Cooperative Fish and Wildlife Research Unit; Institute of Arctic Biology University of Alaska Fairbanks
Don Russell, CircumArtic Rangifer Monitoring and Assessment Network (CARMA)
Darcy Dugan, Alaska Ocean Observing System

DOI: http://dx.doi.org/10.5751/ES-05376-180201

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Abstract

Livelihood systems that depend on mobile resources must constantly adapt to change. For people living in permanent settlements, 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. Food security for Arctic indigenous peoples harvesting barren ground caribou (Rangifer tarandus granti) depends on movement patterns of migratory herds. Quantitative assessments of physical, ecological, and social effects on caribou distribution have proven difficult because of the significant interannual 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 multiyear period. Beginning with spatial and temporal scales developed in previous studies of the Porcupine Caribou Herd of Canada and Alaska, we used satellite collar locations to compute and analyze season-by-season probabilities of movement of animals between habitat zones under two alternative weather conditions for each season. We then built a set of transition matrices from these movement probabilities, and simulated the sequence of movements across the landscape as a Markov process driven by externally imposed seasonal weather states. Statistical tests showed that the predicted distributions of caribou were consistent with observed distributions, 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 interannual variability in the use of their range.

Key words

caribou; markovian; migration; Rangifer tarandus granti; seasonal distribution; simulation; subsistence hunting

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