Seasonal migration of sika deer on Hokkaido Island, Japan

Abstract

We review the large-scale seasonal migration of sika deer on Hokkaido Island, Japan. A total of 57 female deer wintering in the Shiranuka Hills were radio-tracked between April 1997 and May 2002, yielding 7,765 relocations. Ten (18%) of the deer were upward migrants that had summer home ranges lower than or at similar elevation as their winter home ranges, 29 (51%) were downward migrants that had summer home ranges higher than their winter home ranges, and 12 (21%) were the nonmigrants that had overlapping seasonal home ranges. The summer home ranges of migrants were widely scattered over a total area of 5,734 km2. Migration distance of all migrants averaged 35.1 ± 3.6 km (mean ± SE, n = 39, range = 7.2-101.7 km). Deer showed strong site fidelity to their seasonal ranges. The results suggest that snow cover and bamboo grass are the factors affecting seasonal migration of sika deer in eastern Hokkaido. In addition, coniferous cover can be another important factor in the case of the reverse altitudinal migration by the upward migrants. We think the three migration types developed during the process of deer expanding their distribution after a population bottleneck 130 years ago.