Takeshita Rafaela S C, Bercovitch Fred B, Kinoshita Kodzue, Huffman Michael A
Department of Ecology and Social Behavior, Primate Research Institute, Kyoto University, 41-2 Kanrin, Inuyama, Aichi, 484-8506, Japan.
Wildlife Research Center, Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan.
Primates. 2018 May;59(3):215-225. doi: 10.1007/s10329-018-0655-x. Epub 2018 Apr 3.
The ability of animals to survive dramatic climates depends on their physiology, morphology and behaviour, but is often influenced by the configuration of their habitat. Along with autonomic responses, thermoregulatory behaviours, including postural adjustments, social aggregation, and use of trees for shelter, help individuals maintain homeostasis across climate variations. Japanese macaques (Macaca fuscata) are the world's most northerly species of nonhuman primates and have adapted to extremely cold environments. Given that thermoregulatory stress can increase glucocorticoid concentrations in primates, we hypothesized that by using an available hot spring, Japanese macaques could gain protection against weather-induced cold stress during winter. We studied 12 adult female Japanese macaques living in Jigokudani Monkey Park, Japan, during the spring birth season (April to June) and winter mating season (October to December). We collected faecal samples for determination of faecal glucocorticoid (fGC) metabolite concentrations by enzyme immunoassay, as well as behavioural data to determine time spent in the hot springs, dominance rank, aggression rates, and affiliative behaviours. We used nonparametric statistics to examine seasonal changes in hot spring bathing, and the relationship between rank and air temperature on hot spring bathing. We used general linear mixed-effect models to examine factors impacting hormone concentrations. We found that Japanese macaques use hot spring bathing for thermoregulation during the winter. In the studied troop, the single hot spring is a restricted resource favoured by dominant females. High social rank had both costs and benefits: dominant females sustained high fGC levels, which were associated with high aggression rates in winter, but benefited by priority of access to the hot spring, which was associated with low fGC concentrations and therefore might help reduce energy expenditure and subsequent body heat loss. This unique habit of hot spring bathing by Japanese macaques illustrates how behavioural flexibility can help counter cold climate stress, with likely implications for reproduction and survival.
动物在极端气候下生存的能力取决于它们的生理机能、形态结构和行为方式，但往往也受其栖息地形态的影响。除了自主反应外，体温调节行为，包括姿势调整、群体聚集以及利用树木遮风挡雨等，有助于个体在气候变化中维持体内平衡。日本猕猴（Macaca fuscata）是世界上分布最靠北的非人灵长类动物，已经适应了极端寒冷的环境。鉴于体温调节压力会增加灵长类动物体内的糖皮质激素浓度，我们推测，通过利用现有的温泉，日本猕猴在冬季可能会获得抵御天气引起的寒冷压力的保护。我们研究了12只成年雌性日本猕猴，它们生活在日本地狱谷野猿公园，研究时段为春季产仔季（4月至6月）和冬季交配季（10月至12月）。我们采集了粪便样本，通过酶免疫测定法测定粪便中糖皮质激素（fGC）代谢物的浓度，同时收集行为数据，以确定在温泉中停留的时间、优势等级、攻击率和亲和行为。我们使用非参数统计方法来研究温泉沐浴的季节性变化，以及等级与温泉沐浴时气温之间的关系。我们使用一般线性混合效应模型来研究影响激素浓度的因素。我们发现，日本猕猴在冬季利用温泉沐浴来调节体温。在所研究的猴群中，唯一的温泉是一种有限资源，受到优势雌性猕猴的青睐。高社会等级既有代价也有好处：优势雌性猕猴的fGC水平持续较高，这与冬季的高攻击率有关，但它们因优先使用温泉而受益，而这与较低的fGC浓度有关，因此可能有助于减少能量消耗和随后的身体热量损失。日本猕猴这种独特的温泉沐浴习性说明了行为灵活性如何有助于应对寒冷气候压力，这可能对繁殖和生存产生影响。
