Activity patterns in reindeer with domestic vs. wild ancestry

We analyzed GPS-based activity patterns for two wild reindeer (Rangifer tarandus tarandus) herds: Norefjell-Reinsjøfjell with domestic ancestry and larger average body size and Rondane with wild ancestry and smaller body sizes. We compared activity patterns and tested whether these could translate into different energy budgets that in turn contribute to population differences in body weights between the two ancestries. We defined activities and calculated movement rates based on distance moved every 40 min from GPS-fixes during 2005-2007 for 10 females from reindeer with domestic ancestry and 12 females from reindeer with wild ancestry. During May (i.e. calving season), summer and hunting seasons, reindeer with wild ancestry travelled 2.2, 1.8 and 2.1 times further than those with domestic ancestry. Female reindeer of wild ancestry sustained higher movement rates and bigger home range during the seasons from May to the hunting season. While the total daily cost of locomotion in relation to standard metabolic rate (SMR) during bare-ground seasons amounts to 32-37% and 33-48% among reindeer with domestic and wild ancestry, respectively, the daily energy expenditure (DEE) was higher for the females with domestic ancestry because of their higher body weights. Shorter distances travelled in May, summer and during hunt give reindeer with domestic ancestry a compensatory advantage during the growth season translating into bigger body size, compared to reindeer with wild ancestry. Reindeer with both domestic and wild ancestry exhibited nychthemeral activity in all seasons, optimizing activity regardless of daylight. We conclude that the underlying genetic component associated with ancestry is an important driving force for the significant differences in movement patterns, activity and possibly also body weights.