To develop effective conservation and management actions, it is important to examine anthropogenic disturbance patterns and their impact on wildlife. We examined variation in the behavioral and physiological stress response of the Critically Endangered Mexican mantled howler monkeys Alouatta palliata mexicana in relation to two types of anthropogenic disturbance, habitat spatial patterns and presence of humans or their livestock (noise and presence nearby primates). We studied four groups (42 individuals) in two forest fragments at the Los Tuxtlas Biosphere Reserve for a total of 1100 observation hours, during which we recorded the howler monkeys’ vocalizations, locomotion and vigilance. We additionally collected fecal samples to determine the concentrations of glucocorticoid metabolites (fGCM). Howler monkeys vocalized less and moved more when in more spatially disturbed locations and when exposed more time to nearby noise but spent less time in locomotion when humans were present. fGCM were only related to human presence, suggesting that habitat spatial patterns are less of a challenge than human presence. This may be related to the generally unpredictable nature of the latter. Although our study does not allow determining whether the behavioral and physiological responses of howler monkeys to disturbance are costly, from a conservation standpoint it may be more prudent to assume that they are and design strategies to mitigate them. In this sense, actions aimed at reducing anthropogenic noise could benefit the conservation of Mexican mantled howler monkeys.

中文翻译：

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墨西哥洛斯图斯特拉斯的吼猴对局部空间干扰和人类活动的行为和生理应激反应

为了制定有效的保护和管理行动，重要的是检查人为干扰模式及其对野生动物的影响。我们研究了极度濒危的墨西哥披风吼猴 Alouatta palliata mexicana 的行为和生理应激反应与两种类型的人为干扰、栖息地空间模式和人类或其牲畜的存在（噪音和灵长类动物附近的存在）相关的变化。我们对 Los Tuxtlas 生物圈保护区的两个森林碎片中的四组（42 只）进行了总共 1100 小时的观察，在此期间我们记录了吼猴的发声、运动和警觉。我们还收集了粪便样本以确定糖皮质激素代谢物 (fGCM) 的浓度。吼猴在空间越扰乱的地方发声越少，移动越多，暴露在附近噪音的时间越长，但当人类在场时，它们运动的时间更少。fGCM 仅与人类存在有关，这表明栖息地空间模式比人类存在的挑战要小。这可能与后者通常不可预测的性质有关。虽然我们的研究不允许确定吼猴对干扰的行为和生理反应是否代价高昂，但从保护的角度来看，假设它们是并设计减轻它们的策略可能更为谨慎。从这个意义上说，旨在减少人为噪音的行动可能有利于墨西哥披风吼猴的保护。