Growth and condition of three introduced reindeer herds on South Georgia: the effects of diet and density

The patterns of growth and seasonal changes in body weight and fat reserves of three herds of introduced reindeer on the sub-Antarctic island of South Georgia were investigated. Two of the herds, derived from the same stock, were at different densities but the higher density herd was on the better range. In this herd there was a significant growth advantage to the male reindeer, but not to females. The third herd, of a different stock, was also at a lower density on a range which had become overgrazed. The two lower-density herds showed the same annual changes in body weight and only slight differences in the fluctuation of their fat reserves. In addition, body weights in both these herds fluctuated to the same degree as those of a barren-ground caribou in the Northern Hemisphere but fluctuations in the fat reserves of South Georgia reindeer were considerably more severe. The results suggest that the South Georgia reindeer herds are limited by forage availability.