Some birds sleep while flying
Great frigatebirds sleep in flight, mostly with one hemisphere at a time, for minutes at a stretch, on trips that last weeks.
Established2 min read
Rattenborg’s group put EEG and movement loggers on frigatebirds in the Galápagos. During multi-day soaring over the ocean the birds showed slow-wave sleep, usually in one hemisphere, while the other eye’s visual pathway stayed more available. Total sleep in flight was a small fraction of sleep on land.
Unihemispheric sleep was already known in dolphins and ducks. The new fact was the same state, recorded, in an animal that did not touch earth for days. They do not sleep as well aloft as they do on the nest. They sleep enough to still be flying.
Caveats
- The bouts are short. Flight is mostly wakefulness with naps, not an eight-hour cruise on autopilot.
Sources
- 1Rattenborg N. C. et al.. Evidence that Birds Sleep in Mid-flight. Nature Communications 7, 2016.