Abstract: We compared diets of pikas (Ochotona curzoniae) among meadows dominated by Kobresia humilis, Elymus nutans,
and forbs, using micro-histological analysis of stomach contents. Our objective was to explain the effects of changing habitats on pikas,and to examine adaptability and living strategy for pikas. In the Kobersia humilis meadow,main food items were Elymus nutans, Poa spp. , Oxytropis glabra and Oxytropis kansuensis. In the Elymus nutans meadow, main food items were Elymus nutans, Oxytropis glabra, O. kansuensis, K. humilis and Scirpus distigmaticus. In the forb meadow, main food items were E. nutans, O. glabra,O. kansuensis, Poa spp. , Leontopodium pusillum, Anaphalis lactea, Lancea tibetica and Lonicera rupicola. Species selected by pikas differed significantly among habitats. Those plants, which were utilized seldom by pikas in the others meadows, were the main food items since the availability of preference food items decline. Pikas selected 27 plant species all told during plant growing season,but only E. nutans, O. kansuensis and O. glabra were preferred in all three habitats. Pikas fed on a total of 16 plant species the E. nutans meadow, 22 in the K. humilis meadow, and 24 in the forb meadow, with the number species consumed increasing through the spring/ summer time period. The most frequently observed food item also different by habitat: E. nutans of 40. 49% in the E. nutans meadow, O. kansuensis of 23. 65% in the K. humilis meadow, and L.tibetica of 14. 56% in the forb meadow,indicating a generalized diet. The similarity coefficient indicated that pika diets in E. nutans and K. humilis meadows were similar, but both were significantly different from diets in the forb meadow. Pikas appear capable of varying the diets with habitats,suggesting that they can adapt to changing habitat conditions.

Key words: Habitat, Food selection, Plateau pikas

摘要： 本文采用胃内容物镜检分析法,对栖息于青藏高原矮嵩草草甸、垂穗披碱草草甸和杂类草草甸中的高原鼠兔的主要食物组成进行了比较分析,旨在探讨栖息地变化对高原鼠兔食物组成的影响,揭示高原鼠兔对栖息地变化的生存对策和适应性。研究结果表明:在矮嵩草草甸,高原鼠兔主要取食垂穗披碱草、早熟禾、蓝花棘豆和甘肃棘豆;在垂穗披碱草草甸,主要选择垂穗披碱草、甘肃棘豆、蓝花棘豆、矮嵩草和二柱头藨草;在杂类草草甸,喜食植物种类为垂穗披碱草、蓝花棘豆、甘肃棘豆、早熟禾、弱小火绒草、长茎藁本、兰石草和红花岩生忍冬。在整个植物生长季节,高原鼠兔在3 种栖息地共取食27 种植物,其中垂穗披碱草、甘肃棘豆和蓝花棘豆在不同栖息地中选择指数较高,为高原鼠兔优先选择的食物;在不同栖息地,高原鼠兔取食植物有差别,垂穗披碱草草甸为16 种、矮嵩草草甸为22 种,杂类草草甸为24 种;喜食食物比例也存在着明显差别,在垂穗披碱草草甸,垂穗披碱草比例高达40.5% ,在矮嵩草草甸,甘肃棘豆比例也达到23.7% ,而在杂类草草甸,选食比例最高的兰石草仅为14.6% ,说明在该草甸高原鼠兔食物选择呈现泛化趋势。相似性指数分析结果也表明,杂类草草甸中高原鼠兔主要食物组成与其它两种栖息地有较大的区别。从而说明当栖息地植物群落种类组成发生变化后,高原鼠兔可以通过改变其食物组成而适应新的栖息地。