关键词: 岩羊, 卧息地, 主成分分析, 冬季, 贺兰山

Abstract: Winter bedding sites used by blue sheep Pseudois nayaur were studied using transect lines methods in Helan Mountains , Ningxia Hui Autonomous Region from November to December , 2003. Ninety-four sites used by sheep and fifty random plots were located and measured during 25 transects surveys crossing the entire study area. Blue sheep preferred bed sites dominated by elm Ulmus glaucescens , and avoided beds dominated by Chinese red pine Pinus tabulaeformis and Qinghai spruce Picea crassifolia. Sheep showed a strong preference for slopes exposed to the sun, and avoided shady slopes. Comparing bed sites with random plots, bed sites were characterized by lower tree density , lower food abundance , lower wind speed and shallower snow cover. In Mountains blue sheep frequently used caves as their beds , accounting for 62.77 % of total beds. Beds in caves were associated with steeper slopes , more sheltering cover, lower wind speed , higher temperature and no snow cover. Results of principal component analysis showed that the first 7 principal components explained 80.09 % of the total variance among all bed sites habitat variables. PCA indicated that sheltering cover , wind direction , wind speed , snow depth and distance from rocks were importantfactors in bed-site selection.

Key words: Blue sheep ( Pseudois nayaur), Bed site, Principal components analysis, Winter, Helan Mountains