玉里野生動物保護區臺灣水鹿(Rusa unicolor swinhoii)棲地利用與密度估算

Standardized method of estimating population density in large cervids provides information for long-term monitoring, habitat use, etc and is urgently needed in the forest management. Formosan sambar (Rusa unicolor swinhoii) is the largest herbivore in Taiwan, which widely inhabits the mountains ranged from 150 to 3800m in elevation; however, the population size and habitat preference of this species is still unclear. We estimated the population density of sambar in Yuli Wildlife Refuge using faecal accumulation rate mothod (FAR) and dung counts with fixed-width strip transect sampling. The habitat use model was then constructed using multiple regression with forward stepwise selection, where habitat characteristics were regressed against density index of sambar. The average density of sambar in Yuli Wildlife Refuge is 10.6/km2 (SE = 2.26) during 2003-2005 and the population size is around 1,210 (SE = 258). The highest density in the study region is 21.81/ km2 (SE = 3.76) in the Taipin Valley-Mabu Valley. The habitat model explained a significant amount of variation (75.3%), where four habitat characteristics were included (forest-grassland edge, pine forest, non-bamboo grass coverage and diversity of forbs). Sambar prefers the edge of pine forest and bamboo grassland (coefficient: 0.157/ ha, P < 0.001), pine forest (coefficient: 0.115/ ha, P < 0.001), high coverage of non-bamboo grass (coefficient: 0.171/ha, P = 0.001), and low diversity of forbs (coefficient: -0.002/ha, P = 0.001). Our results showed that decomposition rates of Formosan sambar’s dung differed significantly among altitudes and vegetation types, and should be considered when using pellet group count as a measure of habitat use. The high population density of sambar in Yuli Wildlife Refuge can potentially effect on forest renewal and succession and the intense monitoring plan is suggested.