Seasonal home ranges and migration of red deer (Cervus elaphus)

Abstract

1. Many studies have dealt with home range and migratory patterns of Cervid species, but there are few explicit analyses quantifying migratory patterns and home range size as a result of habitat. Red deer is known to perform migrations between seasonal home ranges, but there is little quantitative information specifically on the Norwegian red deer, Cervus elaphus atlanticus. Using position data from VHF-collared and GPS-collared red deer females, this study aimed to address patterns of migration and home range size and how this can be related to habitat use in the Norwegian red deer. 2. I predict a seasonal migration pattern where animals move between winter ranges at low altitude to summer ranges at higher altitudes (H1). I expect spring migration to be slow, following the phenological development of plants (H2). As a consequence of strategies for energy conservation, and snow cover potentially restricting mobility during winter, I predict home range sizes to be smaller in winter than in summer (H3). Assuming that home range size is determined mainly by food quality, I predict that home range size will decrease as the proportion of agricultural pastures increase (H4). I also expect home range size to increase as the animals move higher, into mountainous areas (with smaller and more scattered vegetation patches) (H5). Assuming that the need for shelter is equally important for home range size as available food, an increasing proportion of forest is expected to reduce home range size (H6). 3. I found that a little more than half the animals migrated between separate summer and winter home ranges, and there was a clear selection for elevated areas in the summer. The summer ranges were larger than the winter ranges, but there was no effect of altitude on home range size in the summer. As predicted, forested areas caused a decrease and mountainous areas an increase in home range size, but contrary to predictions, the presence of pastures tended to increase home range size. Since home ranges were larger when incorporating mountainous areas, but were not affected by altitude, I suggest that altitude itself is of less importance to home range size than the accessibility of habitat types. 4. I found that the spring migration was very rapid; contradicting the prediction that migration is driven gradually by plant phenology. The cues of migration seem to differ between topographically different areas, as migration speed is faster in areas with steep hills and appear less related to the gradual green-up in the altitudinal gradient.