Abstract: Studying the diet composition of rodents and their trophic niche not only can reveal the feeding adaptation characteristics of species under the changing alpine meadow environment,but also explore the interspecific relationships of rodents. In Gannan meadow,the diet composition and trophic niche characteristics of plateau pika (Ochotona curzoniae),plateau zokor (Eospalax baileyi),and Himalayan marmot (Marmota himalayana) in harm subregion of rodent pest of subalpine meadow were studied by fecal microstructure analysis. The results showed that the plant species the three rodents ate were basically the same,but the proportion of the same plant was different. The plants that the plateau zokor ate on were mainly Polygonum viviparum and Potentilla edulis,and the intake of Cyperaceae plants was significantly higher than the other two animals. The plateau pika mainly ate Poaceae grasses,the Himalayan marmot mainly ate Poaceae and Asteraceae. The order of trophic niche width was as follows:Himalayan marmot> plateau zokor > plateau pika,the trophic niche overlap between plateau pika and Himalayan marmot was the largest (0.52). Food proportions differentiation and nutritional niche separation of the three species of rodents are the important reasons for their coexistence and resource sharing.

Key words: Gannan meadow, Rodents, Diet, Trophic niche

摘要： 研究啮齿动物的食性及其营养生态位特征不仅可以了解高寒草甸环境变化下物种的食性适应特征，还可探讨多种啮齿动物的种间关系。本研究采用粪便显微组织观察法，分析了甘南草原高原鼠兔（Ochotona curzoniae）、高原鼢鼠（Eospalax baileyi）和喜马拉雅旱獭（Marmota himalayana）3种啮齿动物的食性及营养生态位特征。结果发现：3种啮齿动物所采食的植物种类基本相同，但其比例各异；高原鼢鼠所采食的植物主要是珠芽蓼（Polygonum viviparum）和鹅绒委陵菜（Potentilla anserina）等杂类草，且对莎草科（Cyperaceae）植物的采食量显著高于其它两种动物，高原鼠兔主要采食禾本科（Poaceae）植物，喜马拉雅旱獭则主要采食禾本科和菊科（Asteraceae）植物；营养生态位宽度依次为喜马拉雅旱獭>高原鼢鼠>高原鼠兔，其中高原鼠兔与喜马拉雅旱獭的营养生态位重叠最大（0.52）。3种啮齿动物在食物上存在分化，营养生态位分离，是其共存的重要原因。

关键词: 甘南草原, 啮齿动物, 食性, 营养生态位