Circling for rodents?

It's a well known fact that birds bones are very light and filled with
holes, just like we have sinuses in our head bones. I've pondered how birds
might sense rate of climb many times and I now hold the view that they sense
it via the cavities in their bones - this would provide them with a very
sensitive variometer, the capacity being automatically incorporated so to
speak.

I'm also convinced that birds soar for pleasure as well as because they
might have to (e.g. Pelicans soar when they are migrating and follow similar
climb/glide patterns to us).

I once observed a seagull from the restaurant at the top of the OMPI
building in Geneva - a seagull was already soaring near the ITU building
when suddenly another shot past the window in a fast glide headed straight
for a point below the other seagull, when it got there it pulled up into the
climb underneath the other gull turning in the same direction. Obviously
his/her CSI (Chief Seagull Instructor) had made the point about proper
thermal entry.

Rgds,

Derrick Steed
Does anyone have an idea of how the birds know where to thermal? Do
they have a vario? Where is it? Where is its capacity?
Assuming they breath while thermalling, then I doubt they use their
lungs as capacity... or maybe they stop and sense the air coming out
their noses.
Just wondering...

Uri 4XGJC

(Andy Durbin) wrote in
message
news:...
"Bill Daniels" wrote in message news:...

Most hawks circling low are looking for rodents, not lift.

Bill Daniels


But many times I have shared thermals with Hawks at high altitude.
How did they get there if not by working thermals at low altitude? I
have never been in a thermal with a Red Tailed Hawk that didn't seem
to be trying to optimize climb rate. Turkey Vultures are a different
story. They seem to be happy with any sloppy thermal technique as
long as they maintain altitude.


Andy