12. Frigatebirds
Frigatebirds are true masters of aerial endurance. During their long flights over the ocean, they take micro-naps that last just seconds, all while gliding high above the waves.
They are among the select few bird species capable of unihemispheric slow-wave sleep while airborne, allowing part of their brain to rest without losing control of their flight. This remarkable adaptation helps them remain aloft for weeks at a time. Study