Imagining life permanently suspended in the sky seems like a biological chimera, but for the common swift (Apus apus), solid ground is an almost unnecessary luxury. Landmark research led by Lund University in Sweden showed that these small birds are capable of remaining airborne for ten consecutive months without perching even once.
Equipped with tiny data loggers and accelerometers to record their activity, biologists discovered that swifts spend more than 99% of their long migration and non-breeding period in uninterrupted flight between Europe and sub-Saharan Africa. To sustain such an aerial marathon, they have developed unique biomechanical adaptations:
- Suspended feeding: They catch so-called "aerial plankton" on the wing, consisting of small insects and floating spiders carried by thermal currents.
- High-altitude sleep: At twilight, they climb up to two and three thousand meters in altitude to drift down slowly gliding in circles, a moment they use to take micro-naps with patterns similar to unihemispheric sleep, resting one brain hemisphere at a time.
- Extreme aerodynamics: Their sharp, scythe-shaped wings and fusiform body minimize caloric expenditure, achieving a gliding efficiency that surpasses many human-made gliders.
They only touch ground during the two months of the breeding season to incubate their eggs and feed their chicks. This prodigy of nature completely redefines the known limits of physical endurance in the animal kingdom.
Source: Current Biology (Lund University, 2016)
