Lloyd Neilsen wrote:
There is a term for this and I cannot remember what it is - something like
'whiffling' ??
- the noise being made as the air spills from their wings in a steep descent.
Someone who knows something about aerodynamics can probably answer that. We
never
saw a bird of prey about as Hugo suggests - the impression we got was that it
appeared to occur where the birds were travelling high, probably to a new
feeding
area and upon seeing suitable habitat below, dropped straight down. However,
on a
couple of occasions, we saw a flock split up with each bird going in a different
direction but still straight down to the canopy. Maybe that was an occasion
when
there was a falcon or hawk about and splitting up was an escape manouvre. Have
just
had a very quick scan through Hanzab and surprisingly it seems as though no
mention
is made of this habit. The only other birds I have seen do this is cormorants
I have seen this behaviour in several species, including Cattle Egrets,
Long-billed Corellas,Sulphur-crested Cockatoos, Pacific Black Ducks and Silver
Gulls. The common denominator seems to be that the birds were flying quite high
to start with. I have always assumed that it was simply a quick way to lose
altitude (and probably fun too), prior to landing.
Other interpretations would be interesting.
Cheers
Ian
=======================================
Ian Temby, 1999 Churchill Fellow
Wildlife Damage Control Officer
Secretary/Treasurer, Birds Australia Parrot Association
Flora & Fauna Program
Department of Natural Resources and Environment
4/250 Victoria Parade
EAST MELBOURNE VIC 3002
AUSTRALIA
Phone 613 9412 4429
Fax 613 9412 4586
E-mail
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