First evidence of a 200-day non-stop flight in a bird

Being airborne is considered to be energetically more costly as compared with being on the ground or in water. Birds migrating or foraging while airborne are thought to spend some time resting on the ground or water to recover from these energetically demanding activities. However, for several decades ornithologists have claimed that some swifts may stay airborne for almost their whole lifetime. Here we present the first unequivocal evidence that an individual bird of the Alpine swift ( Tachymarptis melba ) can stay airborne for migration, foraging and roosting over a period of more than 6 months. To date, such long-lasting locomotive activities had been reported only for animals living in the sea. Even for an aerodynamically optimized bird, like the Alpine swift, flying requires a considerable amount of energy for continuous locomotive control. Our data imply that all vital physiological processes, including sleep, can be perpetuated during flight. Being airborne is energetically costly for vertebrates, and migrating birds are expected to spend some resting time on the ground. Here Liechti et al. show that the Alpine swift ( Tachymarptis melba ) can stay airborne for more than 6 months, implying that this bird can sleep in flight.