Bark-Stripping Preference of Sika Deer and Its Seasonality on Mt. Ohdaigahara, Central Japan

Abstract

The recent increase in the sika deer (Cervus nippon) population has caused dieback of overstory trees due to bark-stripping on Mt. Ohdaigahara, central Japan, resulting in decline of the forest and expanding of open dwarf bamboo (Sasa nipponica) grassland. We evaluated bark-stripping preference of sika deer and its seasonality. Deer stripped bark selectively: some species, such as Hondo spruce and Nikko fir, were often debarked while some other species, such as Siebold's beech, not often were. Bark stripping was most intensive during summer when the deer's main forage, S. nipponica, was abundant, suggesting that bark-stripping was not due to food shortages. The nutritive value of bark was lower than that of S. nipponica, which had high crude protein and hemicellulose contents in summer but an inad- equate mineral balance in summer. Sika deer seems to eat bark either to offset the too rich summer forage and/or to attain a proper mineral balance in summer.