2002年4~11月,在蜂桶寨自然保护区对小熊猫的觅食特征和营养对策进行了研究,并采用Vanderloeg和Scavia选择指数Ei衡量小熊猫对竹笋和竹茎年龄的选择程度.结果表明,小熊猫食物由竹叶(70.5%)、竹笋(22.1%)、野果(7.2%)以及毛(0.2%)等组成.小熊猫几乎全以冷箭竹为食,未发现采食短锥玉山竹.春季食物主要由竹叶和竹笋组成,夏秋季主要由竹叶和果实组成,而冬季以竹叶为主.小熊猫对竹笋、竹叶的觅食具有很强的选择性.基径在3 mm以上被采食竹笋,Ei的值为0.071 9~ 0.094 4,竹高在10~70 cm未被采食竹笋,Ei的值为0.149 6~0.198 9.对不同年龄竹茎和竹叶的选择在各个月份间存在变化,4~6月一年生、二年生和多年生竹竹叶Ei分别为0.036 2 、0.224 8和0.487 6,7~8月三者Ei分别为0.007 1、0.002 7和0.009 8,9~11月特别喜食当年生老笋上的竹叶(Ei=0.552 1).此外,小熊猫在6~8月还特别喜食已展开(53.4%)和未展开的卷曲嫩叶(36.3%),不喜食较老的竹叶(10.3%).小熊猫的食性及其对食物的选择体现了在长期进化过程中觅食对策的优化,可最大化觅食过程中的物质或能量摄入.
In order to understand the optimal foraging strategy exhibited by red pandas,field work was conducted from April to November 2002 in Fengtongzhai Nature Reserve,Sichuan Province,China.Results showed that bamboo leaves and shoots accounted for 70.5% and 22.1% of red pandas'diet,respectively.Besides bamboo,fruits of shrubs also were frequently found in feces left by red pandas from August to early November.Red pandas subsisted almost exclusively on Bashania faberi and rejected Yushania brevipaniculata in our study area,which seemed related to the nutrition levels of the bamboo species.Diet of red pandas changes with season.For example,bamboo leaves and shoots in spring,bamboo leaves and fruits of shrubs in summer-autumn and bamboo leaves in winter.Vanderloeg and Scavia selectivity index(Ei) indicated that red pandas is preferred thick and tender shoots in spring,bamboo leaves on one-or two-years old stems from April to June,and for new leaves on old shoots from September to November.No preference was found for stem age when selecting newly formed leaves during July to August.Food selection and feeding strategy exhibited by red pandas assumed to maximize nutrient or energy intake during the foraging process.