https://www.cnet.com/news/incredible-condor-soared-for-100-miles-without-flapping-its-wings/

An Andean condor, one of the largest flying birds on the planet,
soared through the air for 100 miles (172 kilometers) and didn't bother with
flapping its wings.

The scientists took a deep look at the connection between environmental
conditions and the amount of effort large birds put into their flights. To do
this, they attached data recorders to Andean condors that allowed them to log
every single flap of the wings as well as the birds' flight paths.

The study, published on Monday in the Proceedings of the National Academy of
Sciences, found that Andean condors only flap their wings for about 1% of their
flight time. Most of that happened during takeoffs and when flying near the
ground.

The condors' soaring stamina is impressive, but these heavy birds must pick
their battles when it comes to expending energy on wing flaps.