Oral Presentation- Symposium 12th International Mammalogical Congress

Changing migration in the Ya Ha Tinda elk population: When where and why to migrate? (#474)

Evelyn Merrill 1 , Joshua Killeen 1 , Holger Bohm 1 , Jodi Berg 1 , Scott Eggeman 2 , Mark Hebblewhite 2
  1. University of Alberta, Edmonton, Alberta, Canada
  2. W.A. Franke College Of Forestry & Conservation, University Of Montana, Missoula, MT, USA

In most temperate systems, spring migration to high elevations by ungulates is key for increasing energy intake in a variable environment. A trophic mismatch occurs if the timing of migration is not consistent with plant growth either along the migration route or on their summer ranges. Major migrations routes may change over time due to shifts in land use, predation, human disturbance, or their interactions.  We used movement data from 305 elk collared on winter ranges of the Ya Ha Tinda near Banff National Park, Alberta, Canada during 2002-2015 to investigate the routes used, timing and duration of migration, and factors associated with the distributional shifts in migrating herd segments over time in a partially migratory elk herd. Timing of migration across years was most closely associated with plant phenology on summer ranges, rather than information on the winter range. Elk moving to low-elevation ranges migrated earlier and were exposed to higher green vegetation early in the calving season compared to residents or elk migrating to high elevations. Individual elk showed strong fidelity to migration routes between seasons and across years, but the proportion of elk that migrated westward to high elevation ranges declined while the proportion of migrants moving eastward to low-elevation summer ranges increased. Average exposure to bear and wolf predation risk and forest practices was similar along migration routes but not on summer ranges. Changes in forage, predation, and land use along migration routes account for distributional shifts in migrating elk over the past decade.