Not just swift, but with the stamina to be in the air for 10 months without landing…

How do they sleep and fly? No one is sure but do it they must…they are already known as some of the fastest fliers on the planet, migrating from Europe (where they nest) to Africa every year, eating large quantities on insects along the way. Anyone who has seen them ducking and diving chasing bugs through the air column can attest to their speed and dexterity, and their height above the ground is a good indicator of air pressure, since insects fly higher when it rises. It had long been suspected that they spent most of their time airborne due to an absence of roosting areas in Africa, but scientists have now confirmed this by fitting them with tiny tracking devices and following the movements of 19 individuals throughout two years as they moved from Sweden to Central Africa, via Spain and across the Sahara.

The devices measured location, motion and altitude, allowing a close trace of what they got up to. While some of the birds did land now and again, one for 4 whole nights others didn’t touch ground or tree for the full extent of their migration, only landing for the time needed to nest and breed. The rest of the time is spent flying, catching the calories needed to sustain it as they go. While they are not the only birds who spend long periods aloft (frigate birds are one example, see http://bit.ly/2gDV9SG), swifts are by far the record holders with 99% average of their non breeding time spent in the air, most of it in Africa.

As to how they sleep, maybe like whales they only switch off a part of their brain at a time, and never truly rest. They were seen to climb up to 3km altitude at dawn and dusk, gliding gently down towards earth, and maybe having a power nap along the way. Young birds remain in Africa their first few years, and the team speculate that they may spend even more time aloft, and that the performance of the older ones is but a slowing down after the high pace of adolescence. Since they live up to 20 years, the distance flown by your average swift is calculated to be 7 times the distance to the moon and back, not bad for a little birdie.

Loz

Image credit: Photograph: N. Camilleri/Lund University/PA

http://bit.ly/2fpv78nhttp://bit.ly/2gtPrDhhttp://bit.ly/2e0T8k2http://bit.ly/2fyKvOq Original paper, paywall access: http://bit.ly/2gnRozG