How Sleeping Swifts Keep To
Their Course At 10,000 Ft
By Elizabeth Day
The Telegraph - UK

It has no global positioning satellite, no air traffic controls and no pilots, but the swift is capable of flying at the same altitudes as aeroplanes with more sophisticated navigational skill, new research has found.
The birds routinely fly to 10,000ft at night-time, around 4,000ft higher than previously thought. Swifts are also able to navigate through different wind speeds while sleeping, automatically adjusting their flight to stay on a specific course.
The astonishing findings form part of new research conducted by Dr Johan Backman, a specialist in bird migration at Lund University in Sweden. Dr Backman used a tracking radar to study the habits of 225 birds over different one-hour periods.
He found that the birds flew at different altitudes according to the weather - flying in higher and cooler air in summertime. The first comprehensive scientific evidence that swifts attain heights of 10,000ft means that they fly at the same altitudes as many small, private planes. Most commercial flights operate at higher levels - at around 27,000ft across Europe, while Boeing 747s can achieve 45,000ft.
Swifts also adapt their orientation to avoid drifting during their nocturnal flights. The birds are therefore able to judge their position in relation to the wind, not in relation to ground-level landmarks as previously believed.
"We found that swifts have an extraordinary ability to perform orientations in relation to wind," Dr Backman said. "Even the most advanced planes, with very good navigational instruments would probably be unable to judge the wind drift like this. The remarkable thing is that they do all this while flying through the night and sleeping on the wing at these very high altitudes."
In the early days of radar in the 1950s, air traffic controllers would routinely spot unidentified flying objects, referred to as "angels". Dr Backman and his research team now think that these blips could have been sleeping swifts.
"We don't know specifically that the swifts sleep up there," Dr Backman said, "but there are several different studies that have shown through physiological experiments that birds do shut down half their brains at night-time.
"It is more difficult for a bird to orient itself at that altitude because it is not aided by landmarks, but from an aerodynamic point of view, there is less turbulence at that height." Also the birds are above the reach of predators.
Dr Backman carried out his research over three months last summer using tracking radar to maintain continuous contact with a bird, "illuminating" the target with electromagnetic energy, allowing its path to be traced. Graham Madge, a spokesman for the Royal Society for the Protection of Birds, called the discovery "very exciting".
"The swift is one of the least understood and most mysterious birds," he said. "They do have this ability to fly at high altitude for incredibly long distances, but this research has helped to unravel how they achieve the results that they do.
"It is pretty evident that swifts are supreme flyers, although I am somewhat surprised that they fly to such heights. It is very exciting for ornithologists to put hard facts and data to things like this. For every bit of research, however, more mysteries and more questions are thrown up, like what on earth are they eating up there?"
Dawn Bulmer, a spokesman for the British Trust of Ornithology, said: "This is amazing information. To prove that the swift flies at this height and that it manages to move its position according to the wind direction is really quite amazing. People have suspected it for a long time but they haven't been able to prove it. This is an incredible advance."
Approximately 80,000 pairs of swifts migrate to Britain each summer, although the numbers have been declining slightly as modern buildings offer fewer opportunities for nest sites. The birds migrate more than 4,000 miles from Africa to England in late April.
Dr Backman's research will be shown on Animal Camera, to be screened at 8.30pm on BBC1 on Wednesday.
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