| Based on 40 composite samples of fresh feces of blue sheep collected from 10 valleys which located within the range of distribution of blue sheep during April to May2008, May to June2008, September to October 2008 and December 2008 to February 2009, the annual food component and proportion of blue sheep were studied with the fecal micro histological analysis. Results showed that blue sheep consumed 54 plant species or genus from 25 families annually, Poaceae, Rosaceae, Ulmaceae, Leguminosae were at high proportion with high average relative densities (RD):Stipa spp. (27.22%), Poa spp. (14.87%) and Ulmus pumila(18.15%) in each season of a year, and they were the main food of blue sheep.The types of vegetation foraged by blue sheep are seasonally different. Trees had a very high frequency in the food composition, with a relative density (RD) of 30.41% in winter, 19.30% in spring and 21.25% in autumn, lowest in summer at 8.67%. Shrubs take a high proportion in the food composition of blue sheep in spring (RD=22.76%) and winter (RD=34.12%), but lower in autumn (RD=18.24%) and lowest in summer (RD=3.97%). Herbaceous of poaceae is at a very high proportion in the annually food composition of blue sheep, the average RD is 49.48%, but it is lower in winter (27.55%) due to lacking of food, unique vegetation character of feeding habitat and interspecies competition with some other ungulates. Herbaceous of non-poaceae is at a proportion of 10.85% on the average, lower than other three kinds of vegetation.Analyze the food composition and diversity of blue sheep with Shannon-Wiener diversity index (H'), Shannon evenness index (J') and niche width index (B), the result shows that these three indexes are seasonally different. Shannon-Wiener diversity index (H') is highest in winter (3.35) and lowest in spring (2.90), Shannon evenness index (J') is highest in winter (1.07) and lowest in autumn (0.83), the niche width index (B) in winter (6.44) is highest among the indexes in four seasons.
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