抄録
Sixteen spotlight counts were conducted at night between June and August 1998 in an area with a high density of sika deer (Cervus nippon) in Nikko National Park, Japan. Behavioral responses to spotlights were analyzed, and distance sampling techniques (DST) were used to estimate deer den-sity. Deer behavior at the time of sighting and subsequent behavioral responses to spotlighting were recorded. Deer with perpendicular distance ≤ 5 m from the census route showed a flight ratio of 6.3% at the time of sighting, but deer > 5 m showed little flight response. Deer ≤ 5 m showed a relatively high flight response of 4.1-22.2% during census events, while deer further than 15 m exhibited a low flight response. Our results show that the spotlight count method meets the basic theoretical assumptions of the DST.
