Natures wonders: swifts stay aloft most of their lives (Introduction)

by David Turell , Friday, October 28, 2016, 00:50 (2947 days ago) @ David Turell

They are the record holders:

https://www.newscientist.com/article/2110650-swifts-break-record-by-staying-aloft-for-1...

"We long suspected that they sleep and mate on the wing. Now, for the first time, there’s evidence that common swifts probably have to do both, because they spend an astonishing 10 months per year without landing – a world record for sustained flight in nature.

"Their nearest rival is the alpine swift, which flies non-stop for up to six months a year.

"In Europe, common swifts land for two months to breed, spending the nights roosting in their nests. Then they’re off to Africa – where no one has ever found roosting sites belonging to them – before returning again in Europe 10 months later to breed.

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"Swifts can live for up to 20 years, and Hedenström calculates that the distance they fly over their lifetime amounts to travelling to the moon and back up to seven times.

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"Hedenström retrieved the data loggers when the birds returned to Europe. Accelerometers revealed flight trajectories and times when they were grounded. Light sensors enabled the researchers to work out the birds’ geographical location using day lengths and times of sunrise and sunset.

"Hedenström says it’s almost inevitable the birds must sleep on the wing, as long suspected. “Assuming that like other animals, swifts need sleep, logically they must do it in the air,” he says.

"One possibility is that like dolphins and frigate birds swifts can “sleep” by switching off one half of their brain, or sometimes both, for short periods, perhaps as they cruise up and down thermals. “It may be they can find a thermal and go round and round,” he says.

"Hedenström’s team also found that the swifts do two massive ascents each day, one at dawn and the other at dusk, spiralling up to altitudes of 2 or 3 kilometres."

Comment: Why did this flight plan develop? What are its advantages, if any? None is mentioned in the article. Perhaps this is an example of the bush of life with weird forms and life styles for no apparent reason..