Wind energy drives frigate birds to fly for weeks continuously.

Frigate birds use wind power and rising air to stay in the air for several continuous weeks. Henry Weimerskirch at the Centre for Biological Studies in Chizé, France, and his colleagues are equipping large frigate birds with devices to track their movement over the Indian Ocean. Some birds have also been fitted with devices to measure their heart rate and acceleration.

Flight Duration and Distance Traveled

The researchers discovered that the birds remain airborne for up to 48 days, traveling an average distance of 450 kilometers per day, often following the winds around the edge of the massive low-pressure area known as the “Doldrums.”

Flight Method

The birds utilize a “soaring” flight method, rising up to 4000 meters with the help of winds and thermal currents. Frigate birds cannot land on water, but they can glide over long distances in a low-energy state — sometimes without any flapping. This may allow them the opportunity to sleep for up to 12 minutes at a time, enabling them to remain airborne for almost unlimited periods.

Reference: Science 353, 74-78 (2016)

Source: https://www.nature.com/articles/535010a