Heterothermy and torpor as energy saving strategies in Antarctic storm-petrel nestlings

威尔逊风暴海燕Oceanites oceanicus是在南极繁殖的最小的恒温动物。由于体积小，因此能量储存能力有限，威尔逊海燕需要使用有效的策略来科普可预测和不可预测的食物短缺。强烈的波动，粮食供应已观察到内和繁殖季节之间在这个物种。在本研究中，我们的目标是研究如何威尔逊风暴海燕雏鸟使用异温作为一种生理策略，以优化精力充沛的投资和麻木作为一种策略，以确保在不可预测的食物短缺的生存。我们将测试雏鸟的营养状态如何决定体温和静息代谢率，以及这是否受环境温度的调节。作为对食物可预测差异的适应，我们将研究体温和静息代谢率的每日节律。我们将测试，如果威尔逊风暴海燕雏鸟战略性地下调他们的体温和休息代谢率在白天，当成年人不能提供食物。我们将进一步研究雏鸟异温性个体差异的原因和后果。我们预计会损害身体功能，如生长和投资到免疫学有关的体温下降和更多的使用麻痹小鸡提供不太频繁的父母。因此，在威尔逊风暴海燕小鸡的异温性可能有健身的后果之间的权衡减少精力充沛的成本和投资的身体功能，最终决定生存的机会繁殖。作为对食物供应可预测差异的适应，我们将研究在暴风雪等恶劣天气事件期间雏鸟的异温现象，预计暴风雪将变得更加频繁，并经常导致巢穴堵塞。因此，这项研究对该物种适应气候变化具有影响，这既与食物供应减少有关，特别是南极磷虾库存减少，也与暴风雪频率增加有关。

Wilsons storm petrels Oceanites oceanicus are the smallest endotherm breeding in the Antarctic. Given their small size and thus limited energy storage capacities, Wilsons storm petrels need to use efficient strategies to cope with both predictable and unpredictable food shortages. Strong fluctuations in food availability have been observed both within and among breeding seasons in this species. In the present study, we aim to study how Wilsons storm-petrel nestlings use heterothermy as a physiological strategy to optimize energetic investment and torpor as a strategy to ensure survival during unpredictable food shortages. We will test how body temperature and resting metabolic rate are determined by the nutritional state of nestlings, and if this is modulated by ambient temperature. As an adaptation to predictable differences in food availability, we will study daily rhythms of body temperature and resting metabolic rate. We will test if Wilsons storm-petrel nestlings strategically down-regulate their body temperature and resting metabolic rate during daytime when adults cannot deliver food. We will further study causes and consequences of individual differences in heterothermy of nestlings. We expect compromised body functions such as growth and investment into immunology in relation to decreased body temperatures and more use of torpor in chicks provisioned less frequently by their parents. Thus, heterothermy in Wilsons storm-petrel chicks may have fitness consequences through a trade-off between reducing energetic costs and investing in body functions which ultimately determine the chances for survival to breeding. As an adaptation to predictable differences in food availability, we will study heterothermy of chicks during severe weather events such as snow storms, which are predicted to become more frequent and often result in blocking of nests. The study therefore has implications for the adaptation of the species to climate change, both in relation to reduced food availability, especially reduced stocks of Antarctic krill, and increased snow storm frequencies.