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Research article - Peer-reviewed, 2020

Energy Stores, Oxidative Balance, and Sleep in Migratory Garden Warblers (Sylvia borin) and Whitethroats (Sylvia communis) at a Spring Stopover Site

Ferretti, Andrea; McWilliams, Scott R.; Rattenborg, Niels C.; Maggini, Ivan; Cardinale, Massimiliano; Fusani, Leonida


Little is known about how songbirds modulate sleep during migratory periods. Due to the alternation of nocturnal endurance flights and diurnal refueling stopovers, sleep is likely to be a major constraint for many migratory passerine species. Sleep may help to increase the endogenous antioxidant capacity that counteracts free radicals produced during endurance flight and reduces energy expenditure. Here, we investigated the relationship between sleep behavior, food intake, and two markers of physiological condition—the amount of energy reserves and oxidative status—in two migratory songbird species, the garden warbler (Sylvia borin) and the whitethroat (Sylvia communis). In garden warblers, birds with high energy stores were more prone to sleep during the day, while this condition-dependent sleep pattern was not present in whitethroats. In both species, birds with low energy stores were more likely to sleep with their head tucked in the feathers during nocturnal sleep. Moreover, we found a positive correlation between food intake and the extent of energy reserves in garden warblers, but not in whitethroats. Finally, we did not find significant correlations between oxidative status and sleep, or oxidative status and energy stores. Despite our study was not comparative, it suggests that different species might use different strategies to manage their energy during stopover and, additionally, it raises the possibility that migrants have evolved physiological adaptations to deal with oxidative damage produced during migration.

Published in

Integrative Organismal Biology
2020, volume: 2, number: 1, article number: obaa010

Authors' information

Ferretti, Andrea
University of Vienna
McWilliams, Scott R.
University of Rhode Island
Rattenborg, Niels C.
Max Planck Society
Maggini, Ivan
University of Veterinary Medicine Vienna (Vetmeduni)
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Fusani, Leonida
University of Vienna

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