King Charlotte A, Chappell Jackie, Robbins Martha M, Crompton Robin H, Sellers William I, Thorpe Susannah K S
School of Biosciences, University of Birmingham, Birmingham, UK.
Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
J Anat. 2025 May 9. doi: 10.1111/joa.14277.
Western lowland gorillas are the largest and most sexually dimorphic ape that habitually exploits arboreal environments. Their size, robust musculature and specialised adaptations in the hands and feet, which are suited for terrestrial quadrupedal locomotion, make them interesting models for understanding how great apes are able to exploit complex arboreal habitats. We present a comprehensive analysis of the arboreal locomotor ecology of western lowland gorillas by studying their behaviour and ecology in the context of their morphology. A group of fully habituated wild western lowland gorillas was followed for 12 months in Loango National Park, Gabon. Statistical analysis applying regression modelling and Akaike's Information Criterion was used to identify the relationships between locomotor behaviours, height, contextual behaviour, support use, hand posture and body size. Our findings suggest that the gorillas were not restricted in their ability to access and move around in tree canopies because of their size or postcranial morphology. Instead, they exhibited considerable behavioural flexibility and engaged in locomotor behaviours that contradicted classic body size predictions for primates. To offset the risks of moving on small supports, the gorillas used hand-assisted bipedal locomotion on multiple small supports, rather than relying on suspensory locomotion. We suggest that this is linked to their hand dimensions, which have been selected to facilitate efficient quadrupedal walking on the ground. The silverback gorilla engaged in less horizontal locomotion in the canopy, spent less time at heights above 20 m, and used large supports more often than the adult females, blackback and adolescents, but the type and number of supports used did not vary between body size groups. We also found that the reproductive status of the females (presence or absence of small infants) may have shaped how they responded to risks when solving the problem of gap-crossing in the trees. Overall, our results highlight that the gorillas likely prioritised risk minimisation in the supports that they used in arboreal environments at the cost of increased energy expenditure.
西部低地大猩猩是习惯性利用 arboreal 环境的最大且两性异形最明显的猿类。它们的体型、强健的肌肉组织以及手脚的特殊适应性，适合陆地四足运动，这使它们成为理解大型猿类如何利用复杂 arboreal 栖息地的有趣模型。我们通过在形态学背景下研究西部低地大猩猩的行为和生态，对其 arboreal 运动生态学进行了全面分析。在加蓬的洛安戈国家公园，对一群完全习惯化的野生西部低地大猩猩进行了为期 12 个月的跟踪。运用回归建模和赤池信息准则的统计分析，以确定运动行为、高度、情境行为、支撑物使用、手部姿势和体型之间的关系。我们的研究结果表明，大猩猩在树冠层中获取和移动的能力并未因其体型或颅后形态而受到限制。相反，它们表现出相当大的行为灵活性，并参与了与灵长类动物经典体型预测相矛盾的运动行为。为了抵消在小支撑物上移动的风险，大猩猩在多个小支撑物上使用手部辅助的两足运动，而不是依赖悬荡运动。我们认为这与它们的手部尺寸有关，手部尺寸经过选择以利于在地面上高效地四足行走。银背大猩猩在树冠层中的水平移动较少，在 20 米以上高度停留的时间较少，并且比成年雌性、黑背大猩猩和青少年更频繁地使用大支撑物，但支撑物的类型和数量在不同体型组之间没有差异。我们还发现，雌性的生殖状态（是否有小婴儿）可能影响了它们在解决树上跨越间隙问题时应对风险的方式。总体而言，我们的结果突出表明，大猩猩可能在 arboreal 环境中以增加能量消耗为代价，优先将在所用支撑物上的风险最小化。
