On Wed, Jul 16, 2008 at 12:35:58PM +1000, Chris Sanderson wrote:
> I have observed Black-shouldered Kites, Nankeen Kestrels and Brown Falcons
> hovering on regular occasions. I understand Peregrine Falcons are also
> capable of the feat, though I have never seen them do it.
Evan is right. In most cases they would have maintaining a stationary
position with respect to the ground by flying into a headwind - impressive
in itself but not strictly hovering. For most birds energy requirements
are thought to follow have a U-shape with flight and very low speed
flight is either expensive or impossible. Despite kestrels' adaption to
this hunting mode there are suggestions they are incapable of hovering.
I don't know if this is correct - as a variety of birds seem capable of
transient hovering - e.g I think I've seen spinebills, kingfishers,
tyrants and owls hover in still air - and of course hummingbirds.
Andrew
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