Date: 3/30/21 11:18 am
From: Thomas Gilg <tom...>
Subject: [obol] Re: Nailing Scaup Identification
Thanks for the discussion!

Everything I’ve read says “purplish head sheen” is authoritative for Lesser, but I see split opinion on “greenish head sheen” being authoritative for Greater, with some saying greenish can occur on Lessers too. Thoughts?

I’m still trying to get the gestalt of head shape + lip stick + head sheen + flank cleanness solidified in my mind.

Attached are 1/17/2012 picture from inland Brownville where the right two individuals had good green sheen (see IMG_9916), but I opted not to call them Greaters.


From: <obol-bounce...> <obol-bounce...> On Behalf Of Robert O'Brien
Sent: Tuesday, March 30, 2021 12:25 AM
To: obol <obol...>
Subject: [obol] Re: Nailing Scaup Identification

Disclaimer. These photos are of males which have head coloration as a differing feature. Females I guess are structurally the same as males and the wing stripes correspond, so the nail would perhaps be a little more important, but seems to me still pretty hard to discern even in direct comparison

On Tue, Mar 30, 2021 at 12:07 AM Robert O'Brien <baro...><mailto:<baro...>> wrote:
Forgot the photo

On Tue, Mar 30, 2021 at 12:04 AM Robert O'Brien <baro...><mailto:<baro...>> wrote:
As Lars has said, although both are diving ducks, Lesser Scaup seem to prefer smaller or at least shallower water while Greater Scaup are the opposite.
These are an interesting pair, identification wise. (Behaviorally as well, I would guess, but I don't know anything about that).
As found in any field guide:
Lesser Scaup are somewhat smaller with somewhat smaller, narrower bills & a smaller nostril, a purplish head reflection, a more peaked head profile, sometimes with an apparent indentation on the sides of the head, and a shorter wing stripe.
Greater Scaup the opposite in all respects, a greenish head reflection, and a somewhat wider bill and fatter, rounded head.
The head reflection is quite dependent upon the angle and brightness of the sun and can simnply look all dark in poor lighting.
And then there is the 'tip', which allows nailing the identification. Greater Scaup has a much more pronounced, wider nail as Roy has described in detail.
A compromise between the deepwater Columbia and shallower inland ponds is perhaps found at Vanport Wetlands, the ponds west of the Expo Center, that is
At least these waters (largely unvegetated) are close to the Columbia.. This is a good place for direct comparison on a lucky day.
The two attached photos were taken there in late winter last year
As you can see by the camera's numbering, the photos were taken a minute or two apart in good light.
Their bills are pretty similar, but the Lesser's being somewhat more slender; the head peaking is apparent in Lesser. Head reflections correspond to above.
But.....................I'm having a hard time nailing this identification..
I am NO scaup expert, I just took their photos. But the nails on this pair would likely be the last thing I would rely on.
Looking forward to comments from Roy and all others.
Bob OBrien Carver OR

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