Large birds use cliffs as "invisible elevators" to soar without flapping their wings.

Large avian species such as the Andean Condor and the Golden Eagle rely on a phenomenon known as orographic lift. This occurs when horizontal winds encounter a physical barrier like a cliff or mountain range, forcing the air mass to move vertically. By positioning themselves within this rising air, birds can maintain or increase their altitude without the metabolic cost of flapping. A 2020 study published in the journal 'Proceedings of the National Academy of Sciences' monitored Andean Condors and found they flap their wings for only 1% of their flight time. One bird even flew for more than 5 hours and covered 100 miles without a single flap. This efficiency is critical for birds that weigh up to 33 pounds, as the energy required for takeoff and sustained flapping is immense. The physics of this behavior involves the bird finding the 'sweet spot' where the upward velocity of the air exceeds the bird's natural sink rate. In addition to slope soaring, these birds often utilize thermal soaring, which uses columns of rising warm air. However, cliff-side updrafts are more predictable and consistent, providing a reliable 'elevator' system for heavy scavengers and predators. Researchers at Swansea University have used high-tech flight recorders to prove that these birds are masters of reading the invisible landscape of moving air.