THE PENNINGTON FLASH 'MID' SCAUP

IDENTIFICATION RESOLVED?

by Ian McKerchar

During July 2006 an breeding plumaged drake Scaup like aythya was found at Pennington Flash. The bird appeared quite small, approximately equal to Tufted Duck, had a well vermiculated mantle and scapulars, black restricted to the nail of the bill only and a particularly angular shaped head, which bearing in mind the observer's expectations of the returning Lesser Scaup and this birds atleast passing resemblance to that species, is what it was identified as.

The bird was seen by several experienced observers that afternoon and evening and little was said to contradict the original identification, until I received a email from Rob Smallwood expressing his concern over the birds upperwing pattern from a digital image he had taken that evening and had included with the email. The image appeared to clearly show a strong white upperwing bar on the secondaries, extending well onto the primaries, a feature all wrong for Lesser Scaup. The image (and all observations up to this point) was taken in very strong sunlight and I was cautious of jumping to conclusions considering the occasionally misleading nature of assessing digital images, but it was clearly intriguing and further study of the bird in the field (or rather, on the flash) was obviously necessary.

The next morning I visited Pennington with Pete Berry and after quickly locating the bird off the car park it was immediately obvious it was no Lesser Scaup. Andy Makin soon arrived and too expressed discomfort with the bird's identification as a Lesser Scaup, having obtained some digital footage of the bird wing flapping which clearly showed a strong white wingbar along the upperwing. The bird lacked the expected well peaked crown of Lesser Scaup completely, although it still appeared rather angular and square shaped, showed too much green gloss to the head, whilst the vermiculations on the mantle were too fine for Lesser Scaup, although the extremely bright light was not helping in assessing this. Pete and I both agreed that the bill appeared too proportionally large for Lesser Scaup and in a brief front on view, we were both struck by the birds very broad 'beam' (width across the body). Initially however, the bird didn't exactly resemble a Greater Scaup either, it was quite small, lacked the very rounded head and simply didn't look 'right' for that species. Rob Adderley had photographed a male Greater Scaup at Heaton Park Reservoir only several days before and the images of both birds seen side by side were clearly structurally different.

All observers were now in agreement the bird was not a Lesser Scaup and a hybrid became the most popular theory, one which I ultimately disagree with. The following photo essay is intended to give my opinion of the birds true identification.

Above: Despite being taken in very bright sunlight, this image clearly shows the full extent of the white onto the primaries. (photo by Rob Smallwood)

Above: The head shape here is slightly more rounded but still with a slight angle at the rear crown and overall the bird doesn't really look like a Greater Scaup? (photo by Ian McKerchar)

Above: The bright light doesn't help but the vermiculations on the fore mantle and scapulars is particularly fine. (photo by Ian McKerchar)

Above: Here, with a Tufted Duck, it's overall demure size is apparent, although the head shape here is the most Greater Scaup like and the bill is obviously larger and deeper. (photo by Ian McKerchar)

Above: Again, it looks more Greater Scaup like in this image, despite it's small size! (photo by Ian McKerchar)

Above: The white wing bar extending well onto the primaries is obvious even from underneath, but note the oddly square shaped head. (photo by Ian McKerchar)

Conclusions

After closely studying the bird I felt it was most likely a small (runt) Greater Scaup and my thoughts were echoed by Pete Berry and Rob Adderley atleast, both of whom had come to the same conclusion. The reasons for this were as follows:

1/. Plumage wise the bird was identical to Greater Scaup, with a strong green gloss to the sides of the head and very fine vermiculations on the fore mantle and scapulars.

2/. The wing pattern matched Greater Scaup exactly.

3/. Despite it's overall small size, especially when viewed out of the water, it appeared 'bulkier' than Tufted Duck, with a broader beam.

4/. Although the head shape often appeared unusually angular and square shaped at other times it appeared more rounded, particularly on the fore-crown, after which it flattened slightly and displayed a slight angle at the rear-crown. This may possibly be due to some moulting of the head feathers which could conceivably alter the head shape slightly.

Other observers still felt the bird was a hybrid, due to the overall feeling of it being so un-Greater Scaup like when viewed in the field. Judith Smith contacted aythya hybrid 'experts' Eric and Barry Gillham in Suffolk and supplied them with afew images of the bird. They thought the bird may be a Tufted Duck or Greater Scaup x Lesser Scaup, backcrossed to a Lesser.

Whilst I thank and appreciate their valuable opinions, I still feel the bird is more likely a runt Greater Scaup (due to the above), although a Greater x Lesser Scaup hybrid, whilst muted for some time early on by myself and others seems not only unlikely, but very difficult to prove.

So, for all intents and purposes the identification remains un-resolved, unless anybody else has any other ideas, opinions or definitive answers, which I would warmly welcome to be sent to me here.

I would like to thank Rob Adderley, Pete Berry, Andy Makin, Rob Smallwood and Judith Smith for supplying their images and more importantly their opinions and discussions on the identification of this bird.

Ian Mckerchar, August 2006

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