Investigation on multi-level society in primates : intra-specific variation of proboscis monkeys

重点研究环境因素，明确了什么“环境条件”在长鼻猴多层次社会形成中起重要作用。本研究的环境条件是指植被类型：红树林和河滨林。在本研究中，我厘清了栖息在红树林中的长鼻猴的生态和社会结构，并通过对比我之前研究的河滨森林中长鼻猴的生态和社会结构，评价了环境条件对红树林中长鼻猴社会结构的影响。红树林长鼻猴的活动预算与河滨林不同，红树林长鼻猴的觅食时间和吃水果时间都比河滨林长鼻猴多。此外，红树林长鼻猴的饮食多样性极低于河滨林。基于沿河长鼻猴种群分布的数据，阐明了环境因素，尤其是食物的可得性和捕食压力对长鼻猴种群间凝聚力的显著影响。然而，红树林中群体之间的凝聚力程度似乎受到强烈的食物供应的影响。

I focused on environmental factors and clarified what "environmental conditions" were important in formation of multi-level society in proboscis monkeys. Environmental condition in this study means the vegetation patterns : mangrove and riverine forest. In this study, I clarified the ecology and social structureof proboscis monkeys inhabiting mangrove forest, and then evaluated the effects of environmental condition on their social structure in mangrove forest by comparing ecology and social structure of proboscis monkeys inhabiting riverine forest in my former study. The activity budget of proboscis monkeys in the mangrove forest was different from that in the riverine forest : proboscis monkeys in the mangrove forest spent more time for feeding and more time for fruit-eating compared to those in the riverine forest. In addition, the dietary diversity of proboscis monkeys in the mangrove forest was extremely lower than that in the riverine forest. Base on the data of the locations of proboscis monkey groups along the river, we clarified the significant effects of the environmental factors, especially food availability and predation pressure, on the degree of the cohesiveness among the groups in the riverine forests. However, the degree of the cohesiveness among the groups in the mangrove forest seemed to be influenced by strongly food availability.