关键词: 高原鼢鼠, 营养成分, 粮仓, 选择指数

Abstract: In the current paper we sampled plants from winter caches and nearby vicinities of 67 burrow systems of the plateau zokor (Eospalax baileyi). We then calculated the electivity index (EI)of each of the food items based on their relative biomass and divided them into three preference types based on the 95% confidence limit of the mean EI with bootstrap methods:(1) preferred:95% confidence lower limit > 0;(2)changeable:95% confidence lower limit≤0 and
95% confidence upper limit≥0;and (3)rejected:95% confidence upper limit <0. Subsequently,we measured the content of crude protein,crude fiber,crude water-soluble sugars,and crude ash of these food items and then compared them among the three preference types and further tested the correlations between the mean EI and each of these content levels. A total of 67 food items were identified from the caches,of which 39 (preferred,12 items; changeable, 16 items;rejected, 11 items)were found in more than five burrowing systems,constituting over 99% of the total biomass that we sampled. The contents of crude protein,crude fiber,and crude water-soluble sugars (but not crude ash)differed significantly among the three types (P < 0.001). The preferred and changeable types had significantly higher contents of crude protein and crude water-soluble sugars than the rejected types (P < 0. 01). Furthermore,the preferred and changeable types were found to have a significantly lower content of crude fiber as compared to the rejected types (P < 0. 01). However,the three content levels were not significantly different between the preferred and changeable types (P >0.05). Spearman correlation showed that the contents of crude protein (R =0.547,P < 0.001)and crude water-soluble sugars (R =0. 617,P < 0.001)both were significantly and positively correlated with EI while the content of crude fiber was significantly and negatively correlated (R = - 0.707,P < 0. 001). The content of crude ash was not significantly correlated with EI (R =
0.032,P =0.846). Taken together,our results indicate that plateau zokor prefer food items containing higher levels of protein,more water-soluble sugars,and less fiber,but are apparently not sensitive to mineral content.

Key words: Cache, Electivity index, Nutritional content, Plateat zokor (Eospalax baileyi)