Movement, Energetics, and Demography of Norwegian Reindeer

Rebecca Viejou

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:

  1. 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.
  2. Use GPS locations of 304 wild reindeer trajectories to test a series of predictions that follow from the forage quantity hypothesis for migration.
  3. 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.