The common swift can spend up to ten consecutive months in the air, barely touching the ground, which makes a human's flight to another continent seem trivial in comparison.
Back in the 1970s, ornithologist Ronald Lockley suggested such endurance in swifts, but it was only in 2016 that scientists from Lund University in Sweden were able to confirm this by observing the migration of birds between Sweden and the southern Sahara.
Researchers equipped 13 adult swifts with miniature recording devices with accelerometers and light sensors, tracking the activity and route of the birds over several years. It turned out that on the ground, the birds spend an average of only about two months a year — during the breeding season — while for the rest of the time, they are almost entirely in flight, only occasionally touching down for short periods.
Three swifts even spent all ten months of migration without a single landing, despite each bird weighing close to 40 grams. This underscores the extreme aerodynamic efficiency of their bodies and wings.
Scientists link the differences between "long-distance" swifts and those that occasionally land to molting. Birds that managed to stay in the sky the entire time typically renewed their flight feathers and received a higher quality "flying machine."
Swifts expend relatively little energy during flight due to their streamlined bodies and long, narrow wings, which generate lift with minimal expenditure. An additional source of energy comes from constantly hunting insects right in the air. Researchers also suggest that these birds may be able to nap while flying, gaining altitude up to 2–3 kilometers at dawn and dusk, and then slowly gliding down, although this has not yet been proven.
