When the sun never sets: diverse activity rhythms under continuous daylight in free-living arctic-breeding birds

Steiger, S.S., Valcu, M., Spoelstra, K., Helm, B., Wikelski, M. and Kempenaers, B. (2013) When the sun never sets: diverse activity rhythms under continuous daylight in free-living arctic-breeding birds. Proceedings of the Royal Society of London Series B: Biological Sciences, 280(1764), (doi: 10.1098/rspb.2013.1016)

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Abstract

Circadian clocks are centrally involved in the regulation of daily behavioural and physiological processes. These clocks are synchronized to the 24-hour day by external cues (Zeitgeber), the most important of which is the light-dark cycle. In polar environments, however, the strength of the Zeitgeber is greatly reduced around the summer and winter solstices (continuous daylight or continuous darkness). How animals time their behaviour under such conditions has rarely been studied in the wild. Using a radio-telemetry-based system, we investigated daily activity rhythms under continuous daylight in Barrow, Alaska, throughout the breeding season in four bird species that differ in mating system and parental behaviour. We find substantial diversity in daily activity rhythms depending on species, sex and breeding stage. Individuals exhibited either robust, entrained 24-hour activity cycles, were continuously active (arrhythmic), or showed “free-running” activity cycles. In semipalmated sandpipers, a shorebird with biparental incubation, we show that the free-running rhythm is synchronized between pair mates. The diversity of diel time-keeping under continuous daylight emphasizes the plasticity of the circadian system and the importance of the social and life-history context. Our results support the idea that circadian behaviour can be adaptively modified to enable species-specific time-keeping under polar conditions.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Helm, Dr Barbara
Authors: Steiger, S.S., Valcu, M., Spoelstra, K., Helm, B., Wikelski, M., and Kempenaers, B.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Proceedings of the Royal Society of London Series B: Biological Sciences
Publisher:The Royal Society
ISSN:0962-8452
ISSN (Online):1471-2954
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in Proceedings of the Royal Society of London Series B: Biological Sciences 280(1764)
Publisher Policy:Reproduced under a Creative Commons License

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