台灣水鹿族群密度估算方法評估

An Evaluation of Population Density Estimation Methods for Formosan Sambar (＂Rusa Unicolor Swinhoii＂)

偶蹄類動物的族群動態影響著森林的更新、演替及共域動物，尤其在高族群密度時更明顯。台灣近年來水鹿族群量有增多的趨勢，但鮮少針對水鹿族群密度做過估算，也缺乏完整的方法學探討。本研究嘗試利用自動相機，在新康山區的布新營地及拉庫音溪上游設立兩個不同面積及不同相機分佈方式的樣區，以捕捉標放模式估計水鹿的封閉族群密度，並評估適合水鹿族群密度估算的捕獲率模式、回合時間長度、監測總時間長度等。布新營地樣區面積為0.63 km^2，成體水鹿族群密度在2010年8月中為10.8-77隻／km^2，此大範圍的估計值是由不同的緩衝區面積估計值所造成；拉庫音溪樣區的面積為15.2 km^2，成體水鹿族群密度在2010年9月初為9.2-9.9隻／km^2。族群密度在小面積樣區如布新營地可能會被高估，在大面積樣區如拉庫音溪則可能被低估。在各種條件下，捕獲率模式皆以Mh （JK1）的表現最佳且穩定。以一天為一個捕捉回合，估算時間歷時10天左右，是可應用於大部分狀況的方法，其他條件則於文中討論。

Population dynamics of ungulates impact forest renewal and succession and also sympatric species therein, especially at high population density. The Formosan sambar has increased in abundance in recent years, but its density was rarely estimated and the methodology has not been established. This research aimed to use camera traps at two sampling sites, Bushin camping area and upstream of Lakuin river, which differ in size and camera layout to estimate closed-population density of Formosan sambar using the mark-recapture method. This research also evaluated capture probability model, duration of occasion, and total duration of monitoring that is appropriate for estimating adult Formosan sambar density. The Bushin camping area had a density of 10.8-77 adults∕km^2 in mid-August 2010 with an effective area of 0.63 km^2. The wide range of density estimates was due to different estimates of the area of buffer zone. Lakuin River had a density of 9.2-9.9 adults/km^2 in early September 2010 with an effective area of 15.2 km^2. Density tends to be overestimated in a small sampling area such as the Bushin camping area while underestimated in a large one such as Lakuin River. Capture probability model Mh (JK1) performed the best and was stable under various conditions. One day per occasion and a total of 10 days of capture are generally applicable in most situations. Other considerations are discussed in this study.