Friday 23 January 2015

Ring-necked Duck X Scaup Hybrid

An adult Ring-necked Duck X Scaup hybrid, first noted on Jan 5, has been a daily fixture at Burton's Pond and Quidi Vidi in St. John's. Even though I've seen it several times and have had great looks, it still often registers as a slightly odd Ring-necked Duck upon first sight.

But there are a few key things to look for to make sure you have the real deal.

The first think to look for is the peaked head. The head shape essentially looks like that of a Ring-necked Duck (RNDU) - but it is a little less pronounced making you wonder if it might be a Lesser Scaup.

Then you'll notice that the back is quite dark - on scaup the back is a greyish white - easily ruling out either of the scaup species. But the back isn't entirely black, as would be expected on RNDU or Tufted Duck.

RNDU x scaup hybrid:

A number of key features help you rule out a "pure" Ring-necked Duck.
First of all, the back isn't a solid black. There are faint grey lines giving the back a dark grey colour - that is more concentrated towards the front (which is also the case for scaup - the back becomes darker towards the tail).

RNDU x scaup hybrid:

In comparison with the RNDU in the following photo note:
        • no white at the base of the bill
        • less extensive spur on the flanks (on the RNDU below see the white that extends up from the flanks towards the neck)
        • the bill tip is less black
        • the flanks are entirely white whereas on RNDU it is a light grey with a small area of white towards the front

Ring-necked Duck (this one is from the winter of 2013/2014):

As far as I know, there are only 2 Ring-necked Ducks in town this winter. One female, and this male which I believe to be a first winter male:

 In direct comparison with a Tufted Duck, note that the back isn't a solid black (RNDU x scaup hybrid is behind the TUDU):

This photo of a Lesser Scaup shows the small black tip to the bill. Tufted & Ring-necked Ducks have much more extensive black tips. Greater Scaups are similar to Lesser Scaups in this regard.

Overall, the St. John's hybrid duck seems to be intermediate between Ring-necked Duck and scaup in almost every feature:

        • head shape is less peaked than RNDU
        • the black tip to the bill is intermediate between scaup and RNDU
        • there is a white ring around the bill (just proximal to the black tip) - but no white at the base of the bill
        • the 'spur' on the flanks is not as pronounced as on RNDU, but more so than a scaup (which don't really have a spur)
        • back coloration is somewhere between the solid black of RNDU and white/grey of the scaup species

It's hard to know for sure whether its other parent was a Lesser or Greater Scaup. But a few things seem to suggest the Lesser Scaup X RNDU hybrid:

      • that hybrid combination is more regular across the continent (according to eBird)
      • the lack of green in the luminescence of the head also indicates that it probably does not have Greater Scaup genes
      • the wing pattern (as seen on photos by BMt) shows primaries that are darker than the secondaries - again, another pro-Lesser Scaup feature

Maybe next winter it will return to St. John's and we will be struggling to identify its offspring!