In Norway, reindeer are fragmented into roughly 23 wild populations and 76 semi-domestic herding districts. The variation in forage quantity, migratory behaviour, and demography across these populations provide an opportunity to examine the causes and consequences of migration. In this presentation, I will summarize the results of three studies with the following research goals:
- Use forage biomass, digestibility and energy data, and previously defined landscape models of vegetation and geoclimatic variation to develop maps of summer and winter digestible energy across Norwegian reindeer ranges.
- Use GPS locations of 304 wild reindeer trajectories to test a series of predictions that follow from the forage quantity hypothesis for migration.
- Use 15 years of population data for 43 semi-domestic herding districts to test the basic assumption that migrations provide a demographic benefit.
The results of this work suggest that access to winter ranges with high digestible energy may be an important driver of the large-scale seasonal movements of reindeer, with measurable demographic consequences.