云南高黎贡山两种同域分布雉类冬季的食物分析及取食策略

Diet analysis and foraging strategy of two sympatric pheasants at Mt. Gaoligong in winter

本文采用粪便显微分析法对高黎贡山同域分布的白尾梢虹雉(Lophophorus sclateri)与血雉(Ithaginis cruentus)进行食物组成研究,旨在弄清这两种濒危雉类越冬期间(12月—翌年2月)的食谱以及它们对食物资源的竞争状况。结果表明:白尾梢虹雉取食48种植物,血雉取食43种植物,两种雉类的食物多样性指数分别为3.21和3.35,食物生态位重叠指数达0.598,有27种植物被两种雉类共同取食,且在各自食谱中所占比例甚高;较高的食物多样性和食物生态位重叠度表明两种雉类冬季食谱拓宽,并暗示这两种雉类在冬季可能存在食物竞争;食物种类和取食部位的分化是它们得以同域分布和长期共存的基础;结合这两种雉类的食谱特征和野外取食行为,提出它们冬季的取食策略假说,白尾梢虹雉采取以植物根为食和雪后向低海拔迁移寻求替代食物这两种策略来应对冬季食物不足,而血雉则采取集群游荡以扩大种群取食范围的策略。

By means of microscope,we analyzed the winter feces（ December- February） of Sclater＇s Monal（ Lophophorus sclateri） and Blood Pheasant（ Ithaginis cruentus） that occur sympatrically at the alpine habitat of Mt. Gaoligong. Sclater＇s Monal consumed 48 plants and Blood Pheasant consumed 43 plants species,among which 27 plants occurred in both species＇ diet.These mutual food plants comprised the majority of both pheasants＇ diets： 80.09% and 70.69%respectively. Food diversity（ H = 3. 21,3. 35） and food niche overlap（ C_（ih）= 0. 598） in winter were higher than in the other three seasons,indicating that food competition might exist between the two species. Food partitioning was the consequence of competition,as the data showed plant species and plant parts were the two dimensions of the differentiation. That was the basis for their coexistence. Combining the diet and their foraging behaviors,we hypothesized the feeding strategies for these two pheasants. In winter,Sclater＇s Monal would shift its feeding habit from plant leaves to roots due to the food deficiency,which formed its ＂first-choice strategy ＂. But when their suitable habitat is covered by snow,this species would move to low altitude sites searching for plant leaves. This acted as its ＂emergency strategy＂. These two strategies were used by Sclater＇s Monal to deal with food deficiency in winter. However,Blood Pheasant did not change their feeding habits but would gather large populations and explore larger range size,which would supply more food resources for the whole population. This is a different strategy but is obviously good for each individual in the harsh winter.