Lewden, A, Enstipp, MR, Bonnet, B et al. (3 more authors) (2017) Thermal strategies of king penguins during prolonged fasting in water. Journal of Experimental Biology, 220 (24). pp. 4600-4611. ISSN 0022-0949
Abstract
Most animals experience periods of unfavourable conditions, challenging their daily energy balance. During breeding, king penguins fast voluntarily for up to 1.5 months in the colony, after which they replenish their energy stores at sea. However, at sea, birds might encounter periods of low foraging profitability, forcing them to draw from previously stored energy (e.g. subcutaneous fat). Accessing peripheral fat stores requires perfusion, increasing heat loss and thermoregulatory costs. Hence, how these birds balance the conflicting demands of nutritional needs and thermoregulation is unclear. We investigated the physiological responses of king penguins to fasting in cold water by: (1) monitoring tissue temperatures, as a proxy of tissue perfusion, at four distinct sites (deep and peripheral); and (2) recording their oxygen consumption rate while birds floated inside a water tank. Despite frequent oscillations, temperatures of all tissues often reached near-normothermic levels, indicating that birds maintained perfusion to peripheral tissues throughout their fasting period in water. The oxygen consumption rate of birds increased with fasting duration in water, while it was also higher when the flank tissue was warmer, indicating greater perfusion. Hence, fasting king penguins in water maintained peripheral perfusion, despite the associated greater heat loss and, therefore, thermoregulatory costs, probably to access subcutaneous fat stores. Hence, the observed normothermia in peripheral tissues of king penguins at sea, upon completion of a foraging bout, is likely explained by their nutritional needs: depositing free fatty acids (FFA) in subcutaneous tissues after profitable foraging or mobilizing FFA to fuel metabolism when foraging success was insufficient.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017. Published by The Company of Biologists Ltd. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Thermoregulation, Seabirds, Subcutaneous fat, Normothermia, Fat mobilization, Heat loss |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biomedical Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 10 Jan 2019 13:08 |
Last Modified: | 10 Jan 2019 13:09 |
Status: | Published |
Publisher: | Company of Biologists |
Identification Number: | 10.1242/jeb.168807 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140841 |