Seasonal change in browsing by sika deer on hinoki cypress trees on Mount Takahara, central Japan

Browsing by sika deer (Cervus nippon Temminck) on hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) was monitored for approximately 3 years on 300 trees at three sites on Mount Takahara, central Japan. We investigated the seasonal change in browsing on hinoki cypress in relation to the availability of other food plants (dominated by Sasa nipponica Makino et Shibata) and preferred food plants (deciduous broad leaves). Browsing occurred mostly from November to April, while no browsing damage occurred from June to October. Browsing was observed in November, even when the amount of other food plants did not decrease. Therefore, the cause of browsing cannot be fully explained by a decreased availability of other food plants. Comparison of fecal composition and food availability showed that deer had a preference for deciduous broad leaves. The availability of these preferred plants decreased in November and increased in May. Chemical analysis of the hinoki cypress and deciduous broad leaves (crude protein and neutral detergent fiber) showed that the quality of deciduous broad leaves decreased in November, and as a result the quality of hinoki became higher than that of the deciduous broad leaves. Browsing on hinoki cypress occurred when the availability of deciduous broad leaves decreased, and vice versa. These results suggest that the availability of preferred food plants influences browsing on hinoki cypress by sika deer.