The past several days, with the ice edge right at the Champlain Bridge, 
a birder's delight of many waterfowl species has aggregated just west of 
the bridge for easy viewing.  Many additional birds, mostly Common 
Goldeneyes, and sometimes rafts of the ever-mobile Common Mergansers, 
have been spread out all over the mid-lake waters.  Birds also have 
lined the near-shore waters of the New York shore and the mouth of 
Bulwagga Bay.  Little has changed with bird numbers and species during 
the last 5-6 days.

The birds close to the bridge seem in constant motion, with numerous 
species all churning around together.  It has made for great viewing and 
the fun of discovery, though it makes for difficult species counts.  
Scaup have presented their usual difficulty of identification to 
species, and counts of numbers of birds when in constant motion among 
many of birds.  Most birders have spent their time exploring for 
uncommon or rare species, and have not tried to determine species of 
numbers of scaup.  Some have given estimates.

Yesterday morning I took two suites of photos from which to count scaup 
and determine the species ratio.  Counts were made from 38 photos. Some 
of the details are in the checklist at:

http://ebird.org/ebird/vt/view/checklist?subID=S26867667

Empirical data from nature usually end up being rather uncommon 
numbers.  But in this case the ratio of Lesser to Greater Scaup was 3:1 
right on the button!

Ron Payne and I over the years have done a quite a few careful clicker 
counts of large numbers of birds, plus a number of detailed counts from 
photographs.  In our experience, periodically doing careful, detailed 
counts definitely helps calibrate us for making estimates at other 
times.  A few days ago, on Saturday the 9th, at the end of doing our 
sector for the Bald Eagle survey we ended up at the bridge and joined 
part of the parade of birders excitedly viewing all the birds and 
species.  At the end Ron and I compared our casual notices of scaup, and 
the ratio of the species.  We definitely had spent very little time 
assessing the scaup.  We finally settled on a 3:1 ratio Lessers to 
Greaters(!) that day.

Periodic calibration helps.  And that's why I went back to do a 
photo-based count.

Looks like another super birding opportunity at the bridge today .........

Ian