The frequency of extreme weather events, including heat waves, is increasing with climate change. The thermoregulatory demands resulting from hotter weather can have catastrophic impacts on animals, leading to mass mortalities. Although less dramatic, animals also experience physiological costs below, but approaching, critical temperature thresholds. These costs may be particularly constraining during reproduction, when parents must balance thermoregulation against breeding activities. Such challenges should be acute among seabirds, which often nest in locations exposed to high solar radiation and predation risk. The globally endangered bank cormorant Phalacrocorax neglectus breeds in southern Africa in the winter, giving little scope for poleward or phenological shifts in the face of increasing temperatures. Physiological studies of endangered species sensitive to human disturbance, like the bank cormorant, are challenging, because individuals cannot be captured for experimental research. Using a novel, non-invasive, videographic approach, we investigated the thermoregulatory responses of this seabird across a range of environmental temperatures at three nesting colonies. The time birds spent gular fluttering, a behaviour enhancing evaporative heat loss, increased with temperature. Crouching or standing birds spent considerably less time gular fluttering than birds sitting on nests (ca 30% less at 22°C), showing that postural adjustments mediate exposure to heat stress and enhance water conservation. Crouching or standing, however, increases the vulnerability of eggs and chicks to suboptimal temperatures and/or expose nest contents to predation, suggesting that parents may trade-off thermoregulatory demands against offspring survival. We modelled thermoregulatory responses under future climate scenarios and found that nest-bound bank cormorants will gular flutter almost continuously for several hours a day by 2100. The associated increase in water loss may lead to dehydration, forcing birds to prioritize survival over breeding, a trade-off that would ultimately deteriorate the conservation status of this species.

中文翻译：

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在变暖的世界中做父母：濒临灭绝的海鸟对热应激的温度调节反应。

随着气候变化，包括热浪在内的极端天气事件的发生频率正在增加。天气变热导致的体温调节需求可能对动物造成灾难性影响，导致大量死亡。尽管不那么引人注目，但动物在低于但接近临界温度阈值时也会经历生理损失。当父母必须在体温调节与育种活动之间取得平衡时，这些成本在繁殖期间可能特别受限制。在海鸟中，这样的挑战应该是严峻的，它们通常会在暴露于高太阳辐射和掠食风险的地方筑巢。冬季，这种濒临灭绝的濒临灭绝的cor在南部非洲繁殖，面对温度升高，极地或物候变化的空间很小。由于无法捕获个体进行实验研究，因此对濒临灭绝的物种（如cor）的生理研究具有挑战性。使用一种新颖的，非侵入性的影像学方法，我们研究了这只海鸟在三个筑巢地的环境温度范围内的温度调节反应。鸟类度过卵状扑动的时间，这种行为会增加蒸发热损失，并随温度增加。与坐巢的鸟相比，缩或站立的鸟花费的时间少得多（在22°C时少30％），这表明姿势的调节可以调节对热应激的暴露并增强节水效果。但是，蹲伏或站立会使蛋和小鸡在最适度的温度下易受伤害和/或使巢中的内容物容易被捕食，提示父母可以权衡体温调节需求与后代生存。我们对未来气候情景下的温度调节响应进行了建模，发现到2100年，筑巢绑定的河cor每天几乎连续数小时会不断飘动，这是由于水分流失的增加可能导致脱水，迫使鸟类优先考虑生存，而不是繁殖。最终将破坏该物种的保护地位。