Heterothermy in a Small Passerine: Eastern Yellow Robins Use Nocturnal Torpor in Winter

Author(s)
Aharon-Rotman, Yaara
McEvoy, John F
Beckmann, Christa
Geiser, Fritz
Publication Date
2021-12-16
Abstract
<p>Torpor is a controlled reduction of metabolism and body temperature, and its appropriate use allows small birds to adapt to and survive challenging conditions. However, despite its great energy conservation potential, torpor use by passerine birds is understudied although they are small and comprise over half of extant bird species. Here, we first determined whether a free-living, small ~20 g Australian passerine, the eastern yellow robin (<i>Eopsaltria australis</i>), expresses torpor by measuring skin temperature (T<sub><i>s</i></sub>) as a proxy for body temperature. Second, we tested if skin temperature fluctuated in relation to ambient temperature (T<sub><i>a</i></sub>). We found that the T<sub><i>s</i></sub> of eastern yellow robins fluctuated during winter by 9.1 ± 3.9°C on average (average minimum T<sub><i>s</i></sub> 30.1 ± 2.3°C), providing the first evidence of torpor expression in this species. Daily minimum T<sub><i>s</i></sub> decreased with T<sub><i>a</i></sub>, reducing the estimated metabolic rate by as much as 32%. We hope that our results will encourage further studies to expand our knowledge on the use of torpor in wild passerines. The implications of such studies are important because species with highly flexible energy requirements may have an advantage over strict homeotherms during the current increasing frequency of extreme and unpredictable weather events, driven by changing climate.</p>
Citation
Frontiers in Ecology and Evolution, v.9, p. 1-8
ISSN
2296-701X
Link
Publisher
Frontiers Research Foundation
Title
Heterothermy in a Small Passerine: Eastern Yellow Robins Use Nocturnal Torpor in Winter
Type of document
Journal Article
Entity Type
Publication

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