Frigate birds power nap [0] so they can stay aloft for weeks, and other birds have been seen to sleep with half their brain at a time [1].

Pretty cool stuff! Have to wonder when this evolved, and whether it could be mimicked.

0: https://www.audubon.org/news/scientists-finally-have-evidenc...

1: https://en.m.wikipedia.org/wiki/Unihemispheric_slow-wave_sle...

they are just switching between parts of brain, essentially running autopilot, sharks do same, soe it's not really THAT impressive for bird to stay in flight for extended periods, 10 days is nothing spectacular