02.07.2024: Sleeping is restorative and has a considerable influence on the metabolism, among other things. The extent to which the common whitethroat (Curruca communis) - a migratory bird native to large parts of Europe in summer and sub-Saharan Africa in winter - utilises this fitness advantage during its intercontinental flights was investigated in a recently published study led by the University of Veterinary Medicine, Vienna. According to the study, these feathered long-haul travellers only partially rely on the energetic benefits of sleep. Instead, they tend to concentrate on foraging.
In their study, researchers from Italy and Austria investigated the relationship between sleeping behaviour and posture, metabolic state and energy conservation strategies during bird migration in the whitethroat warbler. The fieldwork was carried out on the island of Ponza, located around 50 km off the west coast of Italy and an important stopover site on one of the most important migration routes for Palaearctic passerines.
Metabolic benefits from sleep are not fully utilised
"We were able to confirm that sleeping in a crouched position leads to energy savings in the metabolism, which results in lower vigilance and an associated higher vulnerability to predators. However, the birds showed no changes in their sleeping behaviour in response to the amount of energy reserves stored," says Ivan Maggini from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni Vienna, outlining the key research findings.
According to Maggini, this indicates that the songbirds do not fully utilise the metabolic benefits of sleep, at least in the observed phase of their migration. "We suspect that whitethroats prefer foraging to sleeping for optimal energy management and to maximise efficiency during their stopovers," says the researcher.
Important new findings for nature conservation
According to the researchers, the underlying ecological causes require further studies and a comparative approach. This is particularly important as only long-distance migratory birds have been studied so far, meaning that it is not yet known how species with shorter migrations deal with sleep. In general, studies on sleep are important for nature conservation, as they show how migratory birds use the various resting places. Maggini comments: "These findings are essential in order to maintain and improve the environmental conditions at these resting places, as the survival of numerous bird species depends on them."
Sleep is essential for survival during bird migration
Resting places, where birds rest and replenish their energy reserves, play an important role in overcoming the challenges associated with bird migration. While sleep is considered vital for all organisms, it becomes even more important during migration, when energy management becomes a matter of survival - as previous studies have clearly demonstrated.
The article „Sleep Posture Influences Metabolic Rate and Vigilance in the Common Whitethroat (Curruca Communis)“ by Maia Pastres, Ivan Maggini, Massimiliano Cardinale, Leonida Fusani and Andrea Ferretti was published in „Integrative and Comparative Biology“.
Scientific article
