Primates must select sleeping sites carefully to maximize fitness. In habitats with diminished quality and availability of resources, sleeping site selection becomes an even more crucial aspect of primate survival. We investigated sleeping site selection patterns in northern pigtailed macaques (Macaca leonina) living in a degraded habitat by testing the hypotheses of random selection, predation avoidance, and food proximity. We followed a group of northern pigtailed macaques in Sakaerat Biosphere Reserve, northeastern Thailand, over 14 months between February 2017 and October 2018. We identified 107 total sleeping sites and analyzed the forest structure at 50 sleeping sites and 50 randomly selected available sites. While the rate of reuse was low and random (N = 15), with sleeping sites characterized by a low availability of large and tall trees, the selection pattern was not random, with sleeping sites occurring more often in familiar areas (i.e., high site fidelity), and those with a greater number of stems and a higher canopy. These sleeping site characteristics were likely selected to decrease detection by predators and facilitate macaque escape in case of attack, supporting the predator avoidance hypothesis. However, food proximity also played a key role in sleeping site selection in this degraded habitat. Macaques often slept within, or close to, their first/last feeding site and selected their sleeping sites following food distribution, presumably to maximize energy intake. Our results present a new impact of habitat degradation on sleeping site selection in large primate groups: the use of a high number sleeping sites in order to cope with low availability and scattered distribution of fruit resources.

中文翻译：

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当北方短尾猕猴（Macaca leonina）无法在退化的栖息地中选择理想的睡眠场所时

灵长类动物必须仔细选择睡眠地点，以最大限度地提高健康。在资源质量和可用性下降的栖息地中，睡眠地点的选择成为灵长类动物生存的一个更重要的方面。我们通过测试随机选择、避免捕食和食物接近性的假设，调查了生活在退化栖息地的北猪尾猕猴 (Macaca leonina) 的睡眠地点选择模式。我们在 2017 年 2 月至 2018 年 10 月期间跟踪了泰国东北部 Sakaerat 生物圈保护区的一群北尾猴。我们确定了 107 个总睡眠点，并分析了 50 个睡眠点和 50 个随机选择的可用地点的森林结构。虽然重复使用率低且随机（N = 15），但睡眠场所的特点是大树和高树的可用性低，选择模式不是随机的，睡眠地点更常出现在熟悉的区域（即高地点保真度），以及那些具有更多茎和更高冠层的区域。选择这些睡眠地点的特征可能是为了减少捕食者的发现，并在受到攻击时促进猕猴逃跑，从而支持避免捕食者的假设。然而，在这个退化的栖息地，食物接近度在睡眠地点选择方面也发挥了关键作用。猕猴经常睡在或靠近它们的第一个/最后一个进食地点，并在食物分配后选择它们的睡眠地点，大概是为了最大限度地摄入能量。我们的研究结果展示了栖息地退化对大型灵长类动物睡眠地点选择的新影响：