In arid and semiarid environments, water is a key resource that is limited in availability. During the dry season, perennial water sources such as water pans often are far apart and shape the daily movement routines of large herbivores. In hot environments, endotherms face a lethal risk of overheating that can be buffered by evaporative cooling. Behavioral adjustments are an alternative way to reduce thermal constraints on the organism. The trade-off between foraging and reaching water pans has been studied widely in arid environments; however, few studies have looked into how ambient temperature shapes individual trips between two visits to water. In this study, we tracked during the dry season the movement of eight GPS-collared African elephants (Loxodonta africana) cows from different herds in Hwange National Park, Zimbabwe. This species, the largest extant terrestrial animal, is particularly sensitive to heat due to its body size and the absence of sweat glands. We show that most foraging trips depart from water at nightfall, lowering the average temperature experienced during walking. This pattern is conserved across isolated elephant populations in African savannas. We also observed that higher temperatures at the beginning of the trip lead to shorter trips. We conclude that elephants adjust the timing of foraging trips to reduce the thermal constraints, arguing that further considerations of the thermal landscape of endotherms are important to understand their ecology.

中文翻译：

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温度限制了非洲象觅食旅行的时间和持续时间

在干旱和半干旱的环境中，水是关键资源，供应有限。在干旱季节，多年生水源（如水盘）通常相距较远，它们会影响大型食草动物的日常活动。在炎热的环境中，吸热面临致命的过热风险，可以通过蒸发冷却来缓解。行为调节是减少生物体热约束的另一种方法。在干旱环境中，广泛研究了觅食和到达水盘之间的权衡。但是，很少有研究探讨环境温度如何影响两次出水之间的单个行程。在这项研究中，我们旱季八GPS项圈非洲象的运动（在追踪非洲象）来自津巴布韦万基国家公园的不同种群的牛。该物种是现存最大的陆生动物，由于其体型大和没有汗腺而对热特别敏感。我们显示，大多数觅食之旅在黄昏时都从水里流下来，从而降低了步行过程中的平均温度。在非洲大草原上孤立的象群中，这种模式得到了保留。我们还观察到行程开始时较高的温度会导致行程缩短。我们得出的结论是，大象会调整觅食行程的时间以减少热量限制，认为进一步考虑吸热的热量状况对于理解其生态非常重要。