Variation in the Local Sika Deer Density between Three Areas of Japan with Diverse Climatic Conditions

Sika deer are distributed throughout habitats with various landscape compositions under different climate conditions, although the spatial differences in their population demographics and related factors have rarely been examined. First, we estimated the densityDensity and growth rate of sika deerSika deer in three areas of Japan with diverse climatic conditions (KushiroKushiro in HokkaidoHokkaido, YamanashiYamanashi, and BosoBoso in ChibaChiba) by the fine-spatial-scale (localLocal) and derived globalGlobal density for each area. Second, we examined the effects of environmental variables on the spatial variations in the local density and finite rate of natural increase. The global density for Kushiro exceeded 20 deer/km2 during 2005–2012, while those of the other areas (Yamanashi and Boso) were below 20 deer/km2. However, the extent of local density overlapped between Kushiro, Yamanashi, and Boso, ranging from 3 to 36 deer/km2. Positive influential factors for the local density included the proportions of deciduous broad-leaved forests, mixed forests, artificial meadows, and the annual mean temperature, while the total proportion of residential area was a negative factor. Thus, a high density of up to 40 deer/km2 in any area of Japan appears locally possible, regardless of the climateClimate conditions. The finite rate of population increaseFinite rate of population increase was estimated to range from 0.9 to 1.7, which covers the range of potential sika deer population growthPopulation growth rates. Therefore, the target density to effectively manage and predict sika deer populations should be based on a local scale. Database by 5 km square grid cells applied for sport hunting in Japan would be useful and should be expanded to other prefectures and database for nuisance control.