How long can a bird fly without landing?

The common swiftlet (Apus apus) holds the record for longest flight time, being able to stay in the air for 10 months straight.

The common swiftlet can fly continuously for 10 months. Photo: Dilomski

Traveling by plane for almost a day is already tiring for humans, but that is nothing compared to the capabilities of the common swiftlet ( Apus apus ). Many people will start to feel uncomfortable after only a few hours of flying, even if they just sit still. However, swiftlets can spread their wings for 10 months to fly continuously in the sky.

Welsh ornithologist Ronald Lockley suggested in the 1970s that the common swift could hold the record for flight time. But it took decades for a team of researchers at Lund University in Sweden to confirm it. The study was published in the journal Current Biology in 2016.

The team tracked 13 adult swiftlets, fitting them with tiny data loggers that contained accelerometers to record flight activity and light sensors to locate the birds. Some birds were tracked for years as they migrated from Sweden to the southern Sahara desert in the winter and back.

The results showed that common swiftlets spend most of their time in the air. The birds tracked stayed on land for only two months of the year, settling down to breed. Although some occasionally landed for a short while during the other 10 months, they spent more than 99.5% of their time in the air. Three swiftlets were in the air for the entire 10-month migration, an impressive feat considering their small size, each weighing just 40 grams.

Researchers believe the difference between the long-flying swiftlets and the landing ones may lie in their plumage. The landing ones do not molt their wing feathers, while the continuous flyers molt and grow new flight feathers (long, stiff feathers on the wings and tail that help birds glide).

"The presence or absence of moulting reveals subtle differences in overall condition or parasite problems, and explains the flight behavior of individual individuals within a species," explains study author Anders Hedenström.

Researcher Anders Hedenström calls these data loggers “little backpacks.” Photo: A. Hedenström

How can swiftlets stay in the air for so long? Physical activity takes energy, but the animals have adapted to use relatively little energy during long flights.

“Common swiftlets have evolved to be very efficient fliers, with streamlined body shapes and long, narrow wings that generate lift with little effort,” explains Hedenström. This allows swiftlets to expend less energy. They can also replenish their energy quickly by eating flying insects.

For humans, in addition to in-flight snacks, sleeping is also a way to recharge. But scientists are not sure exactly whether swiftlets do the same. "They may do what cormorants do and sleep while gliding. Every day, at dusk and dawn, swiftlets fly up to an altitude of about 2-3 kilometers. They probably sleep while gliding, but we are not sure," Hedenström said.

Thu Thao (According to IFL Science )

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