The common swift (Apus apus) is a remarkable bird found all over Europe, northern Asia and Africa. Because it migrates into sub-Saharan Africa, and because roost sites have never been found there, some scientists have speculated that it stays aloft during its entire non-breeding season.
A group of Swedish scientists attached data loggers, light sensors, and accelerometers to thirteen common swifts and monitored them for two years. They found that these birds remain airborne for 10 months of their non-breeding periods. All of the birds were airborne >99% of the time, but several didn't land at all during those 10 months. Their work is being published in the journal Current Biology .
Hedenström says that common swifts have adapted to a low-energy lifestyle, but his team does not yet know whether the birds sleep while aloft. "Most animals suffer dramatically from far less sleep loss," says Niels Rattenborg, a neurobiologist at Max Planck Institute for Ornithology in Seewiesen, Germany. "But these birds seem to have found a trick through evolution that allows them to get by on far less sleep."
(Score: 1, Funny) by Anonymous Coward on Monday October 31 2016, @10:56PM
I'd argue that's a much simpler feat. If the buoyancy of your body matches the water of your target level, then you don't have to expend much energy to stay mostly where you are. For example, if a fish suddenly died at such a position, it would mostly remain there, gradually drifting up or down (assuming not eaten).
Even if a bird finds an up-draft to reduce the energy needed to stay aloft, it still has to practice good control to stay in the right spot. If it suddenly died, even if its wings stayed stiff in the same position it was last alive, it would be tumbling down within seconds. Its "death drift rate" (for lack of a better term) would be roughly 50x that of the dead fish, and in a predictable direction: down.
(Score: 3, Funny) by GreatAuntAnesthesia on Tuesday November 01 2016, @10:27AM
Yup. Just waiting now for evolution to come up with bouyant hydrogen-filled swifts.