Oxford scientists `fly' to study birds close-up

Pic of
paraglider Two University scientists have taken to the skies of Africa alongside vultures, kites, eagles, and storks to discover how they use thermal winds to assist their flight and plot their route for navigation.

Dr Tim Guilford, University Lecturer in Animal Behaviour and Fellow of Merton College, and Dr Adrian Thomas, a Royal Society Junior Research Fellow of Linacre College/Zoology, used paragliders to observe birds at close quarters, several thousand feet in the air above the Drakensberg Mountains and the Karoo in South Africa.

Both are expert and keen competition paraglider pilots, who were able to glide silently alongside the birds using only the forces available to the soaring birds themselves.

By following birds into thermals, and climbing with them in the rising air, Dr Guilford, who specialises in animal navigation, discovered that they would often leave long before the thermal had petered out, suggesting that the birds did not need to maximise their lift from the thermal before leaving to find another. He found that vultures with a nine-foot wingspan appear to have acquired detailed knowledge about where they can be confident of finding another thermal on their route.

`Not only are they able to see the same landscape as us, but maybe they can even memorise a landscape full of columns of warm, rising air,' Dr Guilford said.

Close-up inspection of Griffon vultures by Dr Thomas (pictured above left, in flight), using video-filming from air, revealed that their `fingered' wing tip is designed to fold when entering thermal turbulence rather than have a huge downward load imposed on it, which would cause severe fractures.

The researchers encountered a mixed reaction to their flight: while some birds followed the paraglider to take advantage of the thermal, kites mobbed the paraglider, presumably thinking it was a large rival bird.

The expedition was backed by the German chief wing designer of NOVA paragliders, Mr Hannes Pappesh, who is also a biologist. The paraglider`s wings are man's closest attempt at emulating the birds' abilities, such as manoeuvring in a small circle and rapid climbing using thermals.

On their next trip to South Africa, the scientists plan to use a tandem paraglider to overcome the problem of filming the birds while flying at the same time.

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