Good point Erik, usually all the migrating birds I am seeing in PA are
going in generally the same direction, but often high birds will be
going one direction and low birds another ( like upper se, lower sw),
but some of the watching I have done along the gulf coast and atlanic
birds were flying in every direction, likely resulting from a lot of
confused birds circling or heading back inland when they hit the coast.
Birds hitting these barriers will often fly back a few miles inland if
they are not ready to cross, or head againt the wind if they are
course correcting.
Good discussion!
Best,
Mike Lanzone
Sent from my iPhone
On Sep 4, 2009, at 7:31 AM, Erik Johnson <ejoh...@tigers.lsu.edu> wrote:
David et al.,
All the birds are flying the same direction while other critters
have random flight paths.
Is this really a safe assumption? Last night I did some moon watching
and the majority (just barely) of birds were headed westish. But
others were flying south, some northeast, etc. I was fairly confident
these were birds and not bats, but Mike made a good point about optics
(I was using 10x binocs) and wasn't videoing so I have no way to prove
to myself (or you guys) what I was seeing. In any case, I checked out
the radar and there was decent volume, but the radial velocity had a
trend of movement to the SW, but with a lot of scatter. Again, were
these birds? I think so. Perhaps variation in the direction of
movements is more apparent where I am along the gulf coast where
topography and bird ecology (water-crossing avoidance vs not;
trans-gulf vs circum-gulf; etc) significantly alter the behavior of
individual birds. I can imagine that farther north birds are pretty
much bombing south (although no doubt topography and ecology are
important there, too). I have had similar experience listening to
call notes - where you can pick out birds going in all directions. So
I think this phenomenon is real, at least here.
Happy listening,
Erik Johnson
S Lafayette, LA (~40mi N of the Gulf of Mexico)
ejoh...@lsu.edu
On Fri, Sep 4, 2009 at 5:30 AM, David
Mozurkewich<moz...@bellatlantic.net> wrote:
On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote:
I should think that, given distant and fleeting views of such
animals,
there's the potential to over-count birds by accidentally
counting bats
and moths. Any pearls of wisdom on this one?
Ted,
All the birds are flying the same direction while other critters
have
random flight paths. This eliminates most false alarms and is good
enough except when the birds are a minority of your detections.
--
David Mozurkewich
Seabrook, MD USA
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