On 16 January, Jim Davis wrote
>I am writing an article on flight styles in birds. One particular
>technique that birds use to minimize effort in flying is to ride the
>upward air currents (actually a wave) that form on the downwind side of a
>hill or island. There are published examples of seabirds wave-soaring,
>but I would like to know if anyone has seen birds in central Australia
>ride the leeward waves formed behind Ayers rock (Uluru) in Alice Springs.
>If so, want species and any information what they were doing - hunting,
>returning to a roost, etc.
>
I can't help Jim with his Uluru enquiry, but I would like to express a hope
that in his article he covers the matter of birds using their feet in
flying. I'm curious to know how widespread this is after noting that on
Lord Howe Island both Red-tailed Tropicbirds and Sooty Terns do so.
In normal forward soaring flight both seem to tuck their feet in behind
them. But when a tropicbird goes into aerobatic display it fully extends
its webbed feet and uses them as rudders and air brakes. The effect of
seeing this black 'undercarriage' suddenly appear on a snowy white bird, is
quite startling at first sight.
The Sooties are something else again! Like many LHI birds they seem more
curious than wary where human observers are concerned. And Sooties love to
ride air currents, especially if they can get a situation where a wind is
blowing over a ridge top or the top of a cliff and they can ride it just
altering their wing angle and occasionally 'pedalling' like mad with their
webbed feet (also black) so as to remain in the same place relative to the
ground. To have a Sooty 'holding' like that and peering into one's face
from about a metre away, is one of the many simple pleasures offered by
Lord Howe Island.
So. Do other sea-birds with webbed feet also use their feet in flying?
Cheers.
Syd Curtis
H Syd Curtis
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