Greater and Lesser Scaup

Summary of Responses

Here is a summary of the seven responses I got to the three scaup photos I posted a couple of days ago. First, a bit more background. I purposely didn't mention it in my post, but photos 1 and 2 showed the same individual from two different angles. Photo 3 was taken a few minutes later, and may or may not have shown the same bird, I don't know. Here are the "votes."

   Photo 1

   6 Greater
   1 Lesser

   Photo 2

   4 Greater
   3 Lesser

   Photo 3

   6 Greater
   1 Lesser


I thought they were each Greater, so you can add one more vote for Greater to each of the summaries above if you want to count my opinion.  Most of the seven respondants mentioned the same field marks that I did, regardless of whether they judged those marks to indicate a Greater or Lesser. One person mentioned that Greaters have lighter colored backs than Lessers. Another mentioned that Greaters tend to ride lower in the water and look broader on the water than Lessers.

The most interesting things to me were: 1) No one implied that they were 100% confident. Everyone tempered their response with some qualifier like "I believe" or "I think". But perhaps they were just being modest?  And 2) There was a variety of responses even among those people I consider to be experienced, reputable birders. Clearly this is not an easy species pair to identify.

Thanks to Craig Fosdick, Keith Archibald, Cliff Weisse, Stephen Peterson, Buck Russell, Jay Langford, and Eric Huish for contributing their thoughts. Below are excerpts from their emails, with names removed, in case you want to read more.

Good birding,

Ryan P. O'Donnell
Department of Biology and the Ecology Center
Utah State University
5305 Old Main Hill
Logan, UT 84322-5305

Excerpts from emails:

"I'm on the fence, but I think it probably is a Greater. I just read Sibley's scaup sidebar in the Big Sibley, and it is not reassuring. I like the picture showing the scaup looking almost head-on (twds the observer). The bill looks pretty good in that shot, nice and big and wide and broad, with a nice big nail, but it would be nice to have a Lesser Scaup bill next to it. The bird does not have a peaked head, and the two Lessers (?) sleeping to the left of it apparently do, and they also have darker more heavily marked backs. So, I think I'm ok with
Greater Scaup. I can see that head color is essentially useless (as Sibley says), because except for the nearly head-on shot, the head color of the Greater appears to be the same as the Lessers; some sort of

"I think the scaup in your photos are all Lessers. The highest point on the head is behind the eye, bill base is less than half the height of the head (more than half the head height on Greater), "jowls" don't look that wide in the one front view and the nail looks narrow in the same shot. Hope this is helpful."

"I believe that is a Greater Scaup, (I think there are at least two in one of your pics, the other one has its head underneath its wing), based on the round shape of the head, the whiter side.
Check out Utahbirds side-by-side comparison."

"I used the same criteria that you listed in your email. I believe that you have a greater in your photos, but am very curious to read what others think. What lens are you using on your camera?" [Those shots were taken with a Pentax W30 digital camera held up to the eyepiece of a Nikon Sky and Earth spotting scope with a 20x eyepiece.]

"Photo 1: appears to be GREATER with rounded head. Whitish body lacks heavier, coarser barring of LESSER. Photo2: possible peaked crown indicates LESSER? Photo3: (from left to right) #1&#2 difficult to ID. #3; GREATER. #4; LESSER. Based on comparing head profiles. Also, #3 appears to have whitish body which #4 lacks, but this could be due to the light/angle of photo."

"I agree with [the previous author] on the ID. But I think bird #4 in photo #3 is a Ring-necked Duck and the two on the left Lesser Scaup."


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