Doctoral Dissertation Improvement: Diet, Ranging Patterns and Social Behavior of Lar Gibbons at Huai Kha Khaeng, Thailand: Exploring the Limits of Flexibility

在Thad Bartlett博士的指导下，Lydia Overbaugh将在泰国怀卡亨野生动物保护区（HKK）探索濒临灭绝的白掌长臂猿的行为灵活性程度。香港动物园的白掌长臂猿生活的环境在很多方面都是独一无二的。首先，这片森林比其他白长臂猿研究地点要干燥得多，降雨量不到其他地方的一半，这使得这片森林成为白长臂猿活动范围内的生态极端。其次，森林是东南亚最大的连续保护区的一部分，这导致了人为压力的减少，同时保持了一个基本完整的大型哺乳动物群落（包括大象、老虎、8种昼夜活动的灵长类动物、2种豹和2种犬科动物）。最后，长臂猿栖息于香港香港公园的马赛克景观中，包括季节性干常绿、山地常绿、混交林和落叶双香林类型。这提供了一个独特的机会来研究白掌长臂猿如何在其范围的极端和栖息地的多样性中对生态差异作出反应。为了确定栖息地质量如何影响长臂猿的行为和生态，本文将对6个长臂猿社会群体的觅食和活动行为进行为期12个月的研究，以验证以下预测：第一，常绿森林中的长臂猿(i)有更小的活动范围和更少的每天旅行，（ii）花费更少的时间觅食，（iii）有更高质量的饮食；第二，这些差异是由果树密度所显示的本土质量差异造成的。目前关于人类进化的假设倾向于将人类行为和饮食灵活性的增加作为我们血统成功的解释。通过研究一种近亲猿类的灵活性程度，我们可以更好地评估灵活性是人类独有的创新这一论断。正如许多长臂猿研究人员所描述的那样，长臂猿依赖于常绿森林，这项研究将展示白掌长臂猿应对生态边缘栖息地的方式。此外，长臂猿主要是一夫一妻制的，但在一些种群中，一妻多夫制和一夫多妻制的发生率很高，这些现象与生态差异有关，如季节和地理资源的可用性。因此，这个项目将增加我们对栖息地质量在维持白掌长臂猿社会一夫一妻制中的作用的理解。拟议的项目将协助研究生培训和增加妇女对科学研究的参与，同时促进一个为少数民族服务的机构。此外，建立一个新的实地基地将为培训泰国实地助理和指导美国本科生提供机会。这项提议的研究最切实的影响是它对灵长类动物保护的适用性。通过更好地了解不同生态条件下的行为灵活性程度以及该物种的生态极限，该项目将为白掌长臂猿的保护政策提供信息。这些知识也可以暂时用于保护目的，在缺乏其他更严重濒危的长臂猿物种的全面知识。

Under the guidance of Dr. Thad Bartlett, Lydia Overbaugh will explore the degree of behavioral flexibility in the endangered white-handed gibbon in the Huai Kha Khaeng Wildlife Sanctuary (HKK), Thailand. White-handed gibbons living at HKK inhabit an environment that is unique in many ways. First, the forest is considerably drier than other white-handed gibbon study sites, receiving less than half the amount of rainfall than elsewhere, making this forest the ecological extreme of the range of white-handed gibbons. Second, the forest is part of the largest continuous protected area in Southeast Asia, which has led to the reduction in anthropogenic stresses while maintaining a largely intact large mammal community (including elephant, tiger, 8 diurnal primates, two leopards and two canids). Finally, gibbons at HKK inhabit a mosaic landscape, including seasonally dry evergreen, hill evergreen, mixed deciduous and deciduous dipterocarp forest types. This presents a unique opportunity to examine how white-handed gibbons respond to ecological differences at the extreme of their range and in a diversity of habitats. To determine how habitat quality impacts gibbon behavior and ecology, the feeding and ranging behavior of 6 gibbon social groups will be studied over a period of 12 months to test the following predicitions: first, that gibbons in evergreen forest will (i) have smaller home ranges and travel less per day, (ii) spend less time foraging, and (iii) have a higher quality diet; and second, that these differences are a result of differences in home range quality as indicated by the density of fruiting trees.Current hypotheses in human evolution favor an increase in the behavioral and dietary flexibility of Homo as an explanation for the success of our lineage. By examining the degree of flexibility present in a more distantly related ape species, we can better evaluate the assertion that flexibility is a uniquely human innovation. As many gibbon researchers have described gibbons as being dependent upon evergreen forest, this study will demonstrate the ways in which white-handed gibbons cope with ecologically marginal habitats. Furthermore, gibbons are primarily monogamous, but significant rates of polyandry and polygyny have been recorded for some populations and these occurrences have been linked to ecological differences such as seasonal and geographic resource availability. This project will therefore increase our understanding of the role of habitat quality in the maintenance of social monogamy in white-handed gibbons.The proposed project will assist in graduate student training and increase the participation of women in scientific research while promoting a minority-serving institution. Additionally, the establishment of a new field site will provide opportunities for training Thai field assistants and instructing US undergraduate students. The most tangible impact of the proposed research is its applicability to primate conservation. By better understanding the degree of behavioral flexibility under distinct ecological conditions and at this species' ecological extreme, this project will inform conservation policies for white-handed gibbons. This knowledge can also provisionally be used for conservation purposes in the absence of comprehensive knowledge of other more critically endangered gibbon species.