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

• Applicant: Professorin Petra Quillfeldt, Ph.D.
• Subject Area: Oceanography
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257052966

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.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• International Connection: Argentina
• Participating Persons: Dr. Nestor Coria; Marcela Mónica Libertelli