As global temperatures reach record highs, threats posed by climate change to biodiversity become ever more severe. For endotherms, maintaining body temperature within safe bounds is fundamental for performance and survival. Animals routinely modify their behavior to buffer physiological impacts of high temperatures (eg ceasing activity, seeking shade). However, this can impose substantial costs related to missed opportunities to engage in other important activities, with potentially large but often overlooked consequences for survival and reproduction. Here, we outline behavioral trade-offs birds and mammals face in navigating thermal landscapes and associated challenges of balancing energy, water, and time budgets; review the rapidly expanding knowledge in this field; and summarize examples – across taxa – of fitness costs during hot weather. We argue that a shift is needed in evaluating the impacts of heat on birds and mammals, and that fitness costs of missed opportunities must be explicitly integrated into climate-change vulnerability frameworks.

中文翻译：

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机会成本和鸟类和哺乳动物对气候变暖的反应

随着全球气温创下历史新高，气候变化对生物多样性构成的威胁变得越来越严重。对于吸热动物，将体温保持在安全范围内是性能和生存的基础。动物通常会改变它们的行为以缓冲高温的生理影响（例如停止活动、寻找阴凉处）。然而，这可能会因错失参与其他重要活动的机会而造成巨额成本，对生存和繁殖可能产生巨大但往往被忽视的后果。在这里，我们概述了鸟类和哺乳动物在导航热景观时面临的行为权衡以及平衡能量、水和时间预算的相关挑战；回顾该领域迅速扩展的知识；并总结在炎热天气下健身成本的例子——跨类群。