The common swiftlet (Apus apus) holds the record for the longest flight, with the ability to stay in the air for 10 months continuously. This is a feat that leaves humans in awe as many of us start to feel uncomfortable after just a few hours of flying, even if we are sitting still. However, swiftlets have evolved to be very efficient fliers and can spread their wings for 10 months without stopping.
In fact, Welsh ornithologist Ronald Lockley first suggested that common swifts could set flight time records in the 1970s. It wasn’t until decades later that a group of researchers at Lund University in Sweden were able to confirm this through their research. Their findings were published in the journal Current Biology in 2016.
The researchers monitored 13 adult swiftlets by attaching tiny data recorders to them. The device contained an accelerometer to record flight activity and a light sensor to locate the bird. Some of the birds were tracked for years as they migrated from Sweden to the southern Sahara desert in winter and then returned.
The results showed that common swiftlets spend most of their time in the air. The tracked birds only stay on land for two months of the year, settling in to breed. Although some birds occasionally land during the remaining 10 months, their flight time still accounts for more than 99.5%. Three swifts even stayed in the air for the entire 10 months of migration, an impressive feat considering their small size, each weighing only about 40 grams.
Researchers believe that the difference between swiftlets that fly long distances and those that land may lie in their plumage. Birds that land do not change their wing feathers, while those that fly continuously lose their feathers and grow new flight feathers, which helps them fly efficiently.
Common swiftlets have evolved to be very efficient fliers, with streamlined body shapes and long, narrow wings that generate lift with little effort. This helps them consume less energy during long flights and quickly replenish energy by eating flying insects. Scientists are still unsure if swiftlets sleep while flying or not, but they do know that they can soar to heights of about 2-3 km at dusk and dawn.
Overall, it is truly remarkable how common swiftlets have adapted
