On Fri, 23 Jan 1998, Andrew Sorensen wrote:
> >Not sure why they wouldn't just fly off.
>
> A lot less energy is used diving rather than flying. It takes a lot of
> energy to get a goose sized body off the water.
>
Most of the bigger geese would be at more peril trying to take off as
well. A dive can occur in a brief instant. Since the eagle is at the low
end of a shallow parabolic flight, a dive would take the bird out of range
for the requisite amount of time before the eagle, a bigger bird, could
turn.

On the other hand, a big bird could
incapacitate a bird trying to take off more easily--once committed to
taking off if a goose, it seems the goose would not have a choice about
diving for several more seconds. Even if the goose abandoned take off,
its momentum would carry it along the top of the water for several seconds
in a direction where turning the head for defense would be nearly
impossible.

There was a young eagle out a Vancouver Lake trying to do this to geese
last Saturday, and all this conversation has obviously made me recall
Newtonian laws of motion and inertia. An interesting application.
RK
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Compiler, Portland, OR CBC, January 3, 1998
President, Oregon Field Ornithologists
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