[obol] Thanksgiving day seabird flight & comments on numbers

[david tracy]

Hi All,

The huge numbers I reported on the Thanksgiving flight justifiably  
raised a few eyebrows among our more veteran, salt encrusted coastal  
observers.  I've reconsidered the extrapolated timed-count of Loons,  
specifically Pacific Loons and think a more appropriate number to  
report would be in the neighborhood of 200,000 Pacific Loons.  The  
methodology was hardly systematic, but I think it may be possible  
500,000 loons flew by at the high end.  But again, with no way to  
characterize the error, especially retroactively, who knows for sure.

One big source of the error is no doubt my lack of experience with  
timed seabird counts.   Another problem is that timed counts are  
difficult to perform when unfathomable numbers keep streaming by.   
You think, I'll count X number of seconds and see how many birds fly  
by... then you get to two and have already lost count when you see  
several strings of like 50-100 birds passing in a few seconds.   Then  
you take this number and apply some multiplier to get a minute or  
hourly average.  Several times, especially when the count would pick  
up after a squall passed, it was nearly impossible to keep in your  
head an estimate of numbers and still get a feel for the mix of  
species.  This can bring one to the point of frustration if your  
trying to be anything close to accurate.  The cool thing was how  
impressive the number of birds was and how they just kept going  
during the daylight hours, except for the rain squalls.

I'm now a big fan of using video to estimate count numbers by holding  
my camera up to the scope in video mode.  I can review the numbers of  
birds in slow motion and the camera registers the time to a tenth of  
a second.  Plus, my new still camera is much more sensitive than my  
older miniDV video camera and the zoom combination with the scope is  
extraordinary. I hope to be more prepared in the future should I be  
so lucky to witness another one of the "mega-flights" that sometimes  
occurs along our coast in the fall.  I'd also encourage any of you  
who might get out to the headlands this time of year to be aware of  
how spectacular the flights can be when the weather turns foul with a  
S-SW component to the winds.

Many thanks to Phil Pickering, Mike Patterson and David Fix for their  
comments & helpful discussion.

david tracy
davect at bendnet.com