Reassessing the definition of basal metabolic rate: Circadian considerations in avian studies

Document Type

Article

Publication Date

Summer 8-13-2019

Journal Title

Comparative Biochemistry and Physiology, Part A: Molecular & Integrative Physiology

Volume Number

237

First Page

1

Last Page

5

Disciplines

Biology | Ecology and Evolutionary Biology | Ornithology | Physiology

Abstract

The importance of daily fluctuations in avian basal metabolic rate (BMR) was introduced in the classic paper by Aschoff and Pohl (1970) characterizing circadian differences. Since that time,there has been a shift in the BMR literature to accept only values measured in the ρ- (resting) phase of the day as true BMR. We argue that α- (active) and ρ-phases both represent BMR, analogous to the plasticity of BMR seen in seasonal variations, or associated with changes in body composition and restrictions in diet. Furthermore, we demonstrate that circadian differences in BMR are not even present in most polar birds and are sometimes absent in a variety of non- passerines. We argue for the ecological value of a 24 h BMR in order to compare with daily energy expenditure (field metabolic rate, FMR), which integrates entire days. We make recommendations for the reporting of BMR with sufficient information so readers will know time, season, etc. res of BMR can be accepted during reproduction in birds, though with some caution.

Notes

Original publication information:

Ellis, H.I. and G.W. Gabrielsen. 2019. Reassessing the definition of basal metabolic rate: Circadian considerations in avian studies. Comparative Biochemistry and Physiology A 237: 110541.

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