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

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.

Some work was done in the early 70's on this. Whatever a bird's "vario" is, it resides in
their ear. Cutting the 8th cranial nerves (which connect the ear to the brain)
extinguished their ability to sense altitude. This work was done in pigeons, (not soaring
birds, who would be expected to have an even better "vario"). Further work (done in a
pressure chamber) indicated that even a pigeon can sense an ambient pressure change
equivalent to climbing 2 feet.

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).

Other research done in the 70's was carried out by a glider pilot in Africa. He wanted to
figure out where all the buzzards went during the middle of the afternoon (all would
disappear every day). They thermaled up, out of sight from the ground. Either for
pleasure,or to cool off?

"Jim Skydell" wrote in message
...
Other research done in the 70's was carried out by a glider pilot in Africa.
He wanted to
figure out where all the buzzards went during the middle of the afternoon (all
would
disappear every day). They thermaled up, out of sight from the ground. Either
for
pleasure,or to cool off?

Or simply because it takes little energy and makes them temporarily safe
from all ground-bound predators?

Vaughn

I'm also convinced that birds soar for pleasure as well as because they
might have to

Earlier this year sitting in my garden on a hot windless day, I watched a
Buzzard pick up a thermal over a small local wood and climb until it was a
speck in the sky. It then closed its wings and dived at great speed until it
was about fifty feet above the ground, pulled out and then proceeded to
climb again. It repeated the climb, dive, climb manoeuvre three times before
I went indoors. Surely that could not have been for anything other than
pleasure ?

DB

"Silent Flyer" ] wrote in message ...

I'm also convinced that birds soar for pleasure as well as because they
might have to

Earlier this year sitting in my garden on a hot windless day, I watched a
Buzzard pick up a thermal over a small local wood and climb until it was a
speck in the sky. It then closed its wings and dived at great speed until it
was about fifty feet above the ground, pulled out and then proceeded to
climb again. It repeated the climb, dive, climb manoeuvre three times before
I went indoors. Surely that could not have been for anything other than
pleasure ?

DB

Definitely not. I have watched similar behaviour many times. One
particular time I was climbing under an nice fat cu where three
buzzards were climbing in to the cloud out of sight and then diving
out of it about five seconds later, over and over again.

Marcel
-------------
Why walk when you can soar?

??Back in my hang gliding days I participated in a competition at ?Grandfather Mountain in North Carolina - about an 800 foot cliff ?followed by another 800 feet of mountain Ð and the cliff was part of a ?soarable ridge. Grandfather mountain is a tourist attraction with a road ?to the top and a gift shop at the summit. We knew we weren't going to ?soar that day because we had trouble walking into the gift shop. The ?weather station inside was reporting winds in excess of 90 mph. But the ?wind direction was perfect - dead on the ridge.??We didn't soar that day but the local residents did. They have ravens at ?Grandfather mountain - lots of ravens. We were literally hanging on to ?any thing we could because we were afraid of being blown off the ?mountain. And, walking across that suspension bridge between the 2 peaks ?was probably not the smartest move. Anyway, the ravens were soaring the ?flippin' ridge. They had their wings tucked in real close and were just ?zipping along. T
hey were at ridge top level about 30 feet in front of us ?and it was just amazing. I can only guess at what their airspeed was, ?but they were probably moving across the ridge at 20 to 30mph and so ?when you factor in the 90+ mph wind speed, their ASIs were probably ?hitting near 130. You'll never convince me they were flying to catch ?lunch - they were flying because they were having a blast. Of this I ?have absolutely no doubt.??Tony V. LS6-b "6N"?

In article , Tony Verhulst
flippin' ridge. They had
their wings tucked in real close and were just ?zipping along. T
hey were at ridge top level about 30 feet in front of us ?and it was just
amazing. I can only guess at what their airspeed was, ?but they were probably
moving across the ridge at 20 to 30mph and so ?when you factor in the 90+ mph
wind speed, their ASIs were probably ?hitting near 130. You'll never convince me
they were flying to catch ?lunch - they were flying because they were having a
blast. Of this I ?have absolutely no doubt.??Tony V. LS6-b "6N"?

I wonder what Vne is for a raven?
--
Mike Lindsay

I wonder what Vne is for a raven?

African or European? :-)

Tony


--

All good things arrive unto them that wait -
and don't die in the meantime.

Mark Twain

I wonder what Vne is for a raven?

African or European? :-)

Tony

And is it carrying coconuts shells?

take care

Blll

For that matter, what the heck are red-tails doing
up at FL180 in the middle of the summer. They sure
are not spotting food or migrating. And what sort
of O2 saturation levels are they maintaining?








At 15:36 16 July 2004, Bllfs6 wrote:
I wonder what Vne is for a raven?

African or European? :-)

Tony

And is it carrying coconuts shells?

take care

Blll