Heat dissipation rate constrains reproductive investment in a wild bird

• Published in: Functional ecology Vol. 33; no. 2; pp. 250 - 259
• Main Authors: Nord, Andreas, Nilsson, Jan‐Åke, Portugal, Steven
• Format: Journal Article
• Language: English
• Published: London Wiley Subscription Services, Inc 01.02.2019
• Subjects: Animals; Biologi; Biological Sciences; Body mass; Body temperature; Enthalpy; Evolutionary Biology; Evolutionsbiologi; Heat; heat dissipation limit; Heat transfer; heat transfer model; heterothermy hyperthermia; High density lipoprotein; Investment; life-history trade-off; Metabolism; Natural Sciences; Naturvetenskap; Parents; Plumage; reproduction; Sensible heat; sustained energy expenditure; Wild animals; workload
• ISSN: 0269-8463; 1365-2435
• DOI: 10.1111/1365-2435.13243

The “heat dissipation limit” theory (HDL) posits that animals with higher capacity to dissipate metabolic heat can increase reproductive investment. This theory remains untested in the wild. We recently showed that increased workload in a small bird causally relates to maximum body temperature. Here, we have expanded this approach by experimentally facilitating sensible heat transfer rate in nestling‐feeding blue tits—a small bird with high resting‐ and work‐induced body temperatures—through removal of ventral plumage. Feather‐clipped parents did not increase work rate but sired larger, and sometimes heavier, nestlings while maintaining lower body temperature and losing less body mass than controls. Thus, when relieved of the demands to dissipate metabolic heat, parents could invest more into both current (nestling condition) and future (self‐maintenance) reproduction. In accordance with the HDL theory, we conclude that constraints on heat dissipation rate could be a potent mediator of life‐history trade‐offs in wild animals. A plain language summary is available for this article. Plain Language Summary