Putative Ring-necked Duck x Scaup Sp Hybrid on Sabattus Pond, 4/11/16

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On Monday, April 11th, Jeannette and I found a fascinating duck, clearly of the genus Aythya, at Sabattus Pond in Sabattus.  Off of Martin’s Point Park in the southwest corner of the pond, it was hanging out with a mixed flock of Ring-necked Ducks and Lesser Scaup.

Appropriate enough, because this bird appears to be a hybrid between Ring-necked Duck (RNDU) and one of the two scaup species! Unfortunately, it was windy, a light rain was falling, and so my phone-scoped attempts at the moderately-distant bird don’t capture this critter in all of his glory. But, they’re good enough for “documentation,” and they offer a chance to do a little analysis.

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2nd from the left, with Ring-necked Ducks.

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2nd from the left, with Lesser Scaup pair and a drake Ring-necked Duck

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With Ring-necked Ducks, Lesser Scaup, and a Bufflehead. Note the apparent size (see below).

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The hybrid (right), with Ring-necked Duck and overexposed Lesser Scaup.

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Note the dark gray back (intermediate between RNDU and scaup) and the gentle curve on the upper edge of the sides, very much like a RNDU. The sides and flanks are very pale gray, also intermediate between RNDU and breeding plumages scaup. There’s also a narrow whiter area on the front of the chest-sides, suggestive of the distinct white “spur” on the sides of RNDU.

The head shape is also intermediate, with a decidedly peak-headed appearance that is closer to RNDU than either scaup, with a fairly straight nape and the peak at the rear of the head. The bill has a wide, but diffuse pale subterminal ring, suggestive of RNDU as well, but not as crisp or narrow (and no additional ring at the base of the bill). I could not see the width of the black tip at this distance, nor did I have the ability to see if there was a maroon ring around its neck (the namesake, if not very field-worthy, ring-neck of the Ring-necked Duck!).

So, it’s clearly part RNDU. Whether the other half is Greater Scaup (GRSC) or Lesser Scaup (LESC), well, that is another question entirely. While RNDU x LESC are the expected species pair (in large part due to an extensively-overlapping breeding range) that Reeber calls “regular,” RNDU x GRSC have also been recorded.

I never saw the spread wing, and I think a detailed and sharp photo of the wingbar could shed some light on the subject. Short of that – or preferably, a DNA analysis – we can’t say for sure, but there were two interesting observations.

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Note the Lesser Scaup on the left and the apparent size of the hybrid compared to it and the nearby Ring-necked Ducks. 

For one thing, in all lights, the head had a distinctly greenish sheen; never purple.  While head color on scaup is notoriously misleading and the interpretation of it is of little value for ID in most conditions, I found it interesting that when seen side-by-side with LESC, it still always looked green as the LESC looked purple (as does RNDU). However, Reeber notes that this hybrid pairing can have a green sheen as well. Remember, not all characteristics of hybrids are necessarily intermediate.

However, the one thing that was intriguing about the possibility of a GRSC  as the other parent (documented, but likely exceptionally rare) is that in almost every angle, the hybrid was noticeably larger than the LESC it was occasionally with, and it usually appeared larger than the RNDUs. Unfortunately, no GRSC were present – they were all on the other side of the pond today. If this bird was indeed larger than RNDU, it’s hard to imagine that one parent was the even smaller LESC. But with a scope shaking in the wind, the play of light on light colors verses dark, and the inherent subjectivity of the judgment of size, I would not swear to it that this bird was large enough to rule out LESC as one of the two parents.  Therefore, I am most comfortable with calling this a Ring-necked Duck x Scaup species hybrid. A rare and beautiful bird regardless!

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The hybrid (left) with Lesser Scaup and Ring-necked Duck.

Reference:
Reeber, Sebastien. 2015. Wildfowl of Europe, Asia, and North America. Christopher Helm: London.

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