Alvaro:
>I am not a raptor
>expert (he is on rec.birds if you want to meet him ;-)

I have :( :( :( he's a shit and pollutes my mailbox with his
idiocy.

> but one of the
>characteristics of migrating Broad-wings over there is that they don't flap.
>If the conditions are such that a flap is needed, you might as well go home
>since Broad-wings are about as lazy a hawk as they come. It struck me as odd
>then that Don would compare Broad-wings with Coops due to flapping style. I
>think this is a perfect example of how the conditions and geography of a
>site affects the impressions we get from birds. I imagine that the Goshutes
>are a mountain site where hawks take a very different tact and migrating
>style than in the Great Lakes, and therefore the impressions one can get
>from the same species will be different depending on where you are studying
>the hawks.

EXACTLY! You've put it perfectly. You are used to huge kettles of
birds soaring in a traffic jam of kettles until they get enough altitude
to make it across the water barrier, I bet.

Birds at our site normally surf the pressure ridge which forms when
we get steady westerlies. You are right about broadwinged hawks
being lazy, soaring, gliding birds - we normally see them on
good thermal, not good "surfing", days, thousands of feet up.

No flapping then! And - they don't come into banding stations
on such days. Broadwinged hawks will not come down into a
station, if they're overhead, even a couple hundred feet,
they stay there.

When they do come in, it's on light-breeze days, enough to break
up thermals, not enough to form a strong pressure ridge. On such
days, all raptors glide near the ridge, and the larger ones don't
seem to get enough lift to just coast. These are the days on which
we tend to trap broadwings. Once they start moving, they seem to
want to move, and if they decide to go after a pigeon lure - unusual
decision for them! - they'll come in pumping. And they have that
kind of loose-limbed look to them when they do so. These are also
days on which Coops need to work, too adding to the confusion.

We trap generally about 10% of the 15-25 broadwings observed at
this site each season. Some of the Great Lakes sites get 30,000
broad-wings on a single crazy day - if they caught even 1%
they'd be busy! But they rarely band more than a handful, due
to the high flight..

- Don Baccus, Portland OR <donb at rational.com>