With the fall bird migration season in full swing, some of us may wonder how these amazing winged animals manage to cover such long distances without sleeping. Now scientists suggest that they may actually take in-flight naps.
In a recent study published in the journal Nature Communications, researchers looked at great frigatebirds—large seabirds that nest on the Galápagos Islands and spend weeks hovering over the ocean in search of fish and other food. The scientists attached small monitoring devices to 14 birds to see what was going on in their brains during nonstop foraging flights that last up to 10 days and cover more than 1,800 miles.
The data from the devices revealed that the birds actually took naps while flying after the sun set.
Sometimes, the birds’ entire brains were asleep during flight, but other times parts of their brains remained vigilant while the birds snoozed midair. The researchers think this brainy trick may allow them to watch out for other birds and thus prevent collisions, study co-author Niels Rattenborg, from the Max Planck Institute for Ornithology in Seewiesen, Germany, says in a statement.
To the researchers’ surprise, the birds only spent about 40 minutes per day sleeping during these long-distance flights. On land, they slept for more than 12 hours a day, and slept deeper. The scientists posit that the birds may be sleep deprived during flights.
In the future, the researchers would like to determine how frigatebirds can function for so long on so little sleep. Humans, for example, fall asleep driving after losing just a few hours of sleep.
“Why we, and many other animals, suffer dramatically from sleep loss whereas some birds are able to perform adaptively on far less sleep remains a mystery,” Rattenborg says.