本研究應用紅外線自動相機來調查常見入侵物種（犬貓）的活動模式，藉由紀錄其個體特徵，引入捉放法與族群模擬技術，以評估犬貓族群數量，與其他獸類在時間和空間資源使用上的潛在衝突。研究樣區在臺北市陽明山地區的天母古道林地，在2014到2016年間，五個相機位點共記錄401張有效照片，及4目8科9種哺乳動物，其中自由犬佔全體活動量的19%，而拍攝清晰可進行個體辨識的犬則有31隻；貓隻則佔全體活動量的14%，出現有12隻貓個體。運用程式Capture模擬估計犬族群量有34±5.3隻；貓族群量13±1.57隻。犬貓族群穩定地出沒於野生動物棲地，並發現其時空使用對特定野生動物有相當程度的重疊。自由犬在春季大量進入森林，特別在自由犬在7時與15時活動的晨昏高峰。犬隻活動模式中，第一型衝突考慮「活動期重疊，且都在地面層覓食」的物種，而棲地利用上犬最易與山羌發生出沒時空重疊。第二型衝突考慮「活動期重疊，但棲地從地面到樹冠層可錯開」的動物，如犬會和獼猴群與松鼠錯開時空資源使用。而貓入侵數量雖低，但卻表現出高度針對性的攻擊行為，會在秋冬食物匱乏之際，積極進入森林捕獵覓食。以貓為主所帶來的第三型衝突，就是「活動期局部錯開，且棲位亦可錯開」，可能發生在貓與白鼻心、或貓與松鼠間。都會林地在未來在兼顧動保工作時，野生動物保育的焦點物種可持續關注：(1)食肉目白鼻心為珍貴稀有的二級保育類動物，隱蔽習性受狗貓活動干擾，其生態適應行為未來值得做為入侵物種監測的指標；(2)山羌與獼猴為三級保育類物種，對自由犬都有行為反應，可以評估野生動物棲地資源的退化衝擊。對這些遭受多重競爭的野生動物而言，自由犬貓入侵後的生態衝擊既是時間配置上的，也是空間領域上的。
Free-ranging dogs and cats have different impacts on wildlife in the urban forest. This study adopted an infrared-triggered camera to identify the individual characteristics of dogs and cats on the Tienmu trail, and estimated the population size of invasive species by the capture-mark-recapture method for feasible conservation solutions. During the period from 2014 to 2016, there were nine species of mammals recorded in four orders and eight families. The free-ranging dogs accounted for 19% of the total activity, with 31 recognizable individuals; cats only accounted for 14%, with 12 individuals. According to the simulation model (Capture), the population estimate of dogs was 34 ± 5.3; the cat population size was 13 ± 1.57. Potential conflicts between dogs/cats and mammals were explored by comparing tempo-spatial resource overlapping, such as seasonal and diurnal activity patterns. A daily overlap of peaked activities suggested that dogs might have conflicts with the muntjac, macaque, and squirrels, especially at the peaks of 7:00 and 15:00. Particularly, the dogs in the spring impact wildlife due to their massive disturbance, social hunting demands, and other multiple pressures. Cats are smaller in biomass, but their hunting behavior is highly aggressive and specific, especially during food shortages in fall and winter. Focal species and behaviors were concerned in the following aspects of endangered wildlife: (1) to monitor the sensitive carnivores like Formosan Gem-faced Civet for coexisting with expanding disturbance of urban dogs/cats; (2) to monitor muntjac and monkey under a heavy overlapping of time and space resources, which might bring unforeseen ecological consequences. Wildlife behaviors can offer a key estimate on the wide-ranging impacts of free-ranging dogs and cats.
