以棲地適合度模式與GPS遙測技術探討臺灣水鹿之空間使用及不同尺度下之棲地選擇方式
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2013
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欲擬訂有效的野生動物保育與經營管理策略，必須先了解動物的空間使用與棲地選擇。臺灣水鹿(Rusa unicolor swinhoii)由於遭受到棲息地的破壞以及狩獵的壓力，被列為保育類野生動物，但目前對其族群狀況及生活史的了解仍十分缺乏，因此本研究首先以棲地適合度模式(habitat suitability modelling)探討其在臺灣的分布情形，並找出影響其分布的關鍵因子，接著利用全球定位系統(global positioning system, GPS)追蹤技術，探討水鹿在活動範圍尺度(home-range scale)、活動範圍內尺度(within-home-range scale)、時間尺度(temporal scale)的棲地選擇，並了解其空間使用方式。棲地適合度模式顯示水鹿偏好棲息在海拔高於1,500 m及遠離公路的地區，臺灣具有7,865 km2 適合水鹿生存的棲地，這些適合的棲地主要分布在中央山脈與雪山山脈，但被三條山區省道切割為五個主要區塊，我們建議監測部分靠近公路的水鹿棲地，未來可嘗試協助其建立亞族群間的交流。此外，我們於2009年7月至2013年7月間藉由GPS項圈追蹤了12隻水鹿(6雄6雌)，發現水鹿具有季節性移動行為，冷乾季(11月到4月)棲息在海拔較低的地區(平均2,483 ± 406 m)，熱濕季(5月到10月)移動到海拔較高的地區(平均2,984 ± 222 m)。在活動範圍尺度，水鹿偏好使用較平坦的地形及較潮溼的坡向(338-67°)，在冷乾季偏好使用闊葉林、針闊葉混淆林、開闊地、及鐵杉林，在熱濕季則偏好冷杉林、箭竹草原、及鐵杉林，整體而言，水鹿能夠廣泛適應各種植被類型。在活動範圍內尺度，水鹿在冷乾季偏好使用太陽照射時數較高的地點。水鹿的棲地選擇也發生在時間尺度上，其在日間距森林的距離明顯短於夜間，顯示森林為水鹿重要的掩蔽處所。在空間使用方面，以最小凸多邊形法(minimum convex polygon)評估水鹿活動範圍大小，發現雄鹿平均年活動範圍為1,078 ± 501 ha，雌鹿平均年活動範圍為1,001 ± 346 ha，活動範圍間的重疊度可高達80.2%，顯示水鹿並未建立排他的領域。雄鹿平均日位移268 ± 90 m，最大日位移6,435 m，雌鹿平均日位移317 ± 135 m，最大日位移4,422 m。活動範圍與日位移在性別間、季節間都沒有顯著差異。整體而言，我們建立了水鹿棲地選擇與空間使用的完整資訊，並推測未來水鹿族群擴張的主要限制是人為干擾的相關因子而非自然環境因子。
Studies on the animal space use and habitat selection are required for the conservation and management of large herbivores. In Taiwan, the Formosan sambar deer (Rusa unicolor swinhoii) is listed as a protected species under the wildlife conservation law because of human overexploitation. However, its population status and life history remains unclear. In this study, we used 2 approaches to investigate habitat selection and space use of sambar deer. In the study on geographical-range scale habitat selection, we used habitat suitability modelling to identify key habitat variables and to predict potential distribution of this species throughout Taiwan. In the studies on space use and habitat selections at home-range scale, within-home-range scale, and temporal scale, we tracked the deer by using global positioning system telemetry. The habitat suitability models indicated the presence of 7,865 km2 suitable habitats for the sambar deer in Taiwan. The deer preferentially used areas that were over 1,500 m in elevation and were distant from roads. The results predicted that deer habitats are mainly located in the Central Mountain Range and Xue Mountain Range of Taiwan. However, the predicted habitats were divided into 5 regions, which were separated by 3 major mountain highways. We recommend that deer hotspots close to the highways should be monitored for the future establishment of connections among different Formosan sambar deer sub-populations. Furthermore, we collected location data from 12 collared deer (6 males and 6 females) between December 2009 and July 2013. The collared deer used higher elevation areas in hot/wet season (mean: 2,984 ± 222 m; from May to October) than in cold/dry season (mean: 2,483 ± 406 m; from November to April), which indicated a seasonal movement behavior. At the home-range scale, the deer preferred broadleaf forest, mixed forest, open habitat, and hemlock forest in the cold/dry season, and preferred fir forest, grassland, and hemlock forest in the hot/wet season. We suggested that sambar deer is a habitat generalist. In addition, the deer preferred to use areas with flatter slopes and mesic aspects (338-67°) at home-range scale, and selected areas with higher solar duration at within-home range scale in the cold/dry season. Habitat selection also occurred at temporal scale. The deer was usually closer to forested habitat in daytime than at night, highlighting its requirement of forest as shelter and cover. Moreover, the mean annual 100% minimum convex polygon home ranges were 1,078 ± 501 ha for males and 1,001 ± 346 ha for females. Overlap in home ranges of sambar deer could be as high as 80.2%, which suggested that the sambar deer did not establish exclusive territory. The mean daily displacements were 268 ± 90 m for males and 317 ± 135 m for females, with a maximum distance of 6,435 m for male and 4,422 m for female. No significant differences of home range size and daily displacement were detected between two sexes and between two seasons. In conclusion, we comprehensively studied the space use and habitat selection of sambar deer at multi-scales. The human-related disturbance would be the main factor affecting sambar deer population expansion in the future.
Studies on the animal space use and habitat selection are required for the conservation and management of large herbivores. In Taiwan, the Formosan sambar deer (Rusa unicolor swinhoii) is listed as a protected species under the wildlife conservation law because of human overexploitation. However, its population status and life history remains unclear. In this study, we used 2 approaches to investigate habitat selection and space use of sambar deer. In the study on geographical-range scale habitat selection, we used habitat suitability modelling to identify key habitat variables and to predict potential distribution of this species throughout Taiwan. In the studies on space use and habitat selections at home-range scale, within-home-range scale, and temporal scale, we tracked the deer by using global positioning system telemetry. The habitat suitability models indicated the presence of 7,865 km2 suitable habitats for the sambar deer in Taiwan. The deer preferentially used areas that were over 1,500 m in elevation and were distant from roads. The results predicted that deer habitats are mainly located in the Central Mountain Range and Xue Mountain Range of Taiwan. However, the predicted habitats were divided into 5 regions, which were separated by 3 major mountain highways. We recommend that deer hotspots close to the highways should be monitored for the future establishment of connections among different Formosan sambar deer sub-populations. Furthermore, we collected location data from 12 collared deer (6 males and 6 females) between December 2009 and July 2013. The collared deer used higher elevation areas in hot/wet season (mean: 2,984 ± 222 m; from May to October) than in cold/dry season (mean: 2,483 ± 406 m; from November to April), which indicated a seasonal movement behavior. At the home-range scale, the deer preferred broadleaf forest, mixed forest, open habitat, and hemlock forest in the cold/dry season, and preferred fir forest, grassland, and hemlock forest in the hot/wet season. We suggested that sambar deer is a habitat generalist. In addition, the deer preferred to use areas with flatter slopes and mesic aspects (338-67°) at home-range scale, and selected areas with higher solar duration at within-home range scale in the cold/dry season. Habitat selection also occurred at temporal scale. The deer was usually closer to forested habitat in daytime than at night, highlighting its requirement of forest as shelter and cover. Moreover, the mean annual 100% minimum convex polygon home ranges were 1,078 ± 501 ha for males and 1,001 ± 346 ha for females. Overlap in home ranges of sambar deer could be as high as 80.2%, which suggested that the sambar deer did not establish exclusive territory. The mean daily displacements were 268 ± 90 m for males and 317 ± 135 m for females, with a maximum distance of 6,435 m for male and 4,422 m for female. No significant differences of home range size and daily displacement were detected between two sexes and between two seasons. In conclusion, we comprehensively studied the space use and habitat selection of sambar deer at multi-scales. The human-related disturbance would be the main factor affecting sambar deer population expansion in the future.
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Keywords
地理資訊系統, 棲地選擇, 活動範圍, 水鹿, 野生動物經營管理, Geographical information system, Habitat selection, Home range, Sambar deer, Wildlife management