An interesting scaup – Greater or Lesser??

Greater and Lesser Scaup often look relatively straightforward to id. from the books, but in the field, at least to me,  they can sometimes be decidedly deceiving and difficult.  I don’t look too hard at ducks as it is, but the subtleties of head shape and bill size can be hard to analyze when faced with a distant raft of scaup. New Haven harbor is an important wintering area for Greater Scaup, the default species you’ll see in good numbers around West Haven.

Near the house this morning, I came across 4 scaup – three obvious male Lessers and a female bird, which I assumed to be a Lesser too, but I was busy trying to photograph them rather than “look” at them –  an unfortunate bad habit associated with trying to photograph and bird at the same time.

2 male Lessers (left) and the female-type bird

They took flight and when reviewing the shots on my camera I noticed the female appeared to be a Greater Scaup, not a Lesser as first assumed.

A typical female Greater Scaup, New Haven, February

This was based on rounded head shape, lots of white around the bill and a rather spatulate bill with broad, dark nail (as on the bird above). The interesting part, is that on the flight shots, the bird shows a wing pattern typically associated with Lesser Scaup in that the white secondaries did not extend onto the inner primaries??? Had I gotten it wrong? After all, it was with three other Lessers.

1st-w male Lesser (below) and same female-type scaup (above)

composite of the female-type bird showing wing pattern

Note the white secondaries end and give way to grayish primaries, a Lesser Scaup feature. Greaters typically show white extending onto the primaries and also have a paler, whitish underwing, whereas Lessers are often more greyish as in the bird above.

So, is the bird a Lesser, or a Greater? From the sitting shots it appears to be a Greater, so how do we explain the  atypical wing pattern. It doesn’t seem to be a lighting artefact. Did i get the id. right?? Do Greater’s often show this wing pattern?? Comments welcome.

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2 Responses to “An interesting scaup – Greater or Lesser??”

  1. Paul French Says:

    Hi Julian

    Take a look at this unoubted Greater Scaup in Lincolnshire recently. http://www.lincsbirds.co.uk/album/displayimage.php?pos=-14187
    Nice wing pattern! I wonder how that would look on a fleeting flyby…??

    Cheers,

    Paul

    • julianhough Says:

      Hi Paul!

      Thanks for the link. I think that light and angle often makes the wing stripe appear either brighter or duller. There seems to be an obvious contrast on the Lincs bird as there is on my female bird which suggest that it is variable or, as some may suggest, possibly a hybrid character. The latter is not my “go to” hypothesis, but in talks with Peter Pyle and other observers, it seems that first-cycle Greaters may be more inclined to show a Lesser-type wing pattern.
      Anyhow, for someone who doesn’t look too hard at ducks, I found this all enlightening and a feature that is more variable than people may realise?

      Thanks again,

      Julian

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