For scaup, I really like to see a good profile look.  Yes, the nail  
is a field mark, and the color of the head, but both are tough  
calls.  The color can vary with the angle of light and is not  
considered reliable.  The nail is a matter of relative size, so need  
another nearby for comparison.
Flank color and overall size are also used, but again, these are  
relative marks and need close examples of both to be much use at any  

The steepness of the forehead, with the peak--the highest point on  
the head-- being well forward is a very good mark.  Beware, though,  
because head shape can change as feathers are compressed/expanded  
with wet/dry.  That is, an actively diving/feeding Lesser may have a  
head shape very much like a Greater until the feathers resume their  
normal, resting position.

Edge Wade
Columbia, MO
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On Mar 29, 2011, at 5:42 PM, Frankie Cuculich wrote:

> Here is the link to photos of the scaups I'm tring to ID. I  
> misspelled the link on
> my first post.  Sorry about that.  Any help on these ducks would be  
> great.
> Thanks and good birding.
> Frankie Cuculich
> Brashear Mo
> Adair Co
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