Dissertation Research: Signal Content and Function in Wild Male Orangutan Long Calls

尽管之前进行了长期的行为研究，但由于猩猩的生活史较长，活动范围大，主要生活在树上，半独居，因此很难全面了解它们的社会组织和繁殖策略。由于成年个体通常是分散的，在雨林栖息地内能见度有限，远距离发声可能在调节个体关系和社会互动（包括繁殖）方面发挥重要作用。已经有强有力的和一致的行为和实验证据证明性内间隔功能，但其他假设，如配偶吸引力或防止性胁迫，还没有经过严格的测试。目前还不清楚可靠的评估线索是否编码在声学特征和呼叫模式中，或者听者是否可以识别单个雄性并将信号者的身份与过去的表现联系起来。本研究旨在测试对雄性长叫声信号内容的预测，检查潜在的功能，并评估婆罗洲和苏门答腊种群中呼叫行为变化的可能决定因素。本研究利用野外录音、局部动物取样和精心控制的重放实验，研究了雄性鸣叫的声音变化、雄性鸣叫的行为模式和行为反应与听者的社会环境、生殖状况和对鸣叫雄性的熟悉程度的关系。雄性猩猩长叫声的信号内容对了解雌性的配偶选择和这种濒危物种的个体间关系的性质具有重要的影响。

Despite previous long-term behavioral studies, a full understanding of the social organization and reproductive strategies of orangutans has been difficult to achieve due to their extended life histories, large home ranges, predominantly arboreal lifestyles and semi-solitary natures. Because adult individuals are normally dispersed and visibility is limited within their rainforest habitats, long distance vocalizations are likely to play an important role in regulating individual relationships and social interactions, including reproduction. There is already strong and consistent behavioral and experimental evidence for an intra-sexual spacing function, but additional hypotheses such as mate attraction or protection against sexual coercion have not been tested rigorously. It is also not yet clear if reliable assessment cues are encoded in acoustic features and calling patterns or if listeners can recognize individual males and associate a signaler's identity with past performance. This research aims to test predictions for the signal content of male long calls, examine potential functions and assess possible determinants of variation in calling behavior among Bornean and Sumatran populations. Using field recordings, focal animal sampling and carefully controlled playback experiments, this study intends to examine acoustic variation in male long calls, the patterns of calling behavior by males and behavioral responses in relation to the listener's social context, reproductive status and familiarity with the calling male. The signal content of male orangutan long calls has important repercussions for understanding female mate choice and the nature of inter-individual relationships in this endangered species.