Wild species use habitats that vary in risk across space and time. This risk can derive from natural predators and also from direct and indirect human pressures. A starving forager will often take risks that a less hungry forager would not. At a highly seasonal and human-modified site, we predicted that arboreal samango monkeys (Cercopithecus albogularis labiatus) would show highly flexible, responsive, risk-sensitive foraging. We first determined how monkeys use horizontal and vertical space across seasons to evaluate if high-risk decisions (use of gardens and ground) changed with season, a proxy for starvation risk. Then, during a subsequent winter, we offered equal feeding opportunities (in the form of high-value, raw peanuts) in both gardens and forest to see if this short-term change in food availability and starvation risk affected monkeys’ foraging decisions. We found that during the food-scarce winter, monkeys foraged outside indigenous forest and in gardens, where they fed on exotic species, especially fallen acorns (Quercus spp.), despite potential threats from humans. Nevertheless, and as predicted, when given the choice of foraging on high-value foods in gardens vs. forest during our artificial foraging experiment, monkeys showed a preference for a safer forest habitat. Our experiment also indicated monkeys’ sensitivity to risk in the lower vertical strata of both habitats, despite their previous extensive use of the ground. Our findings support one of the central tenets of optimal foraging theory: that risk of starvation and sensitivity to the variation in food availability can be as important drivers of behavior as risk of predation.

中文翻译：

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Samango Monkeys (Cercopithecus albogularis labiatus) 在南非 Amathole 山脉的高度季节性、人为改造的景观中管理风险

野生物种使用的栖息地因时空而异。这种风险可能来自天敌，也可能来自直接和间接的人类压力。饥饿的觅食者通常会冒险，而饥饿程度较低的觅食者则不会。在一个高度季节性和人工改造的地点，我们预测树栖萨曼戈猴 (Cercopithecus albogularis labiatus) 将表现出高度灵活、反应灵敏、风险敏感的觅食。我们首先确定猴子如何跨季节使用水平和垂直空间来评估高风险决策（花园和地面的使用）是否随季节变化，这是饥饿风险的代表。然后，在随后的冬天，我们提供了平等的喂养机会（以高价值、生花生）在花园和森林中，看看食物供应和饥饿风险的这种短期变化是否会影响猴子的觅食决定。我们发现，在食物匮乏的冬天，猴子会在原始森林外和花园里觅食，在那里它们以外来物种为食，尤其是落下的橡子（栎属），尽管存在来自人类的潜在威胁。尽管如此，正如预测的那样，当我们在人工觅食实验中选择在花园和森林中觅食高价值食物时，猴子表现出对更安全的森林栖息地的偏好。我们的实验还表明，猴子对这两个栖息地较低垂直地层的风险很敏感，尽管它们之前广泛使用了地面。我们的发现支持最佳觅食理论的核心原则之一：