Lesser Scaup in Derbyshire

The debate surrounding the identity of the Swarkestone 'Lesser Scaup' raises several interesting issues. A number of Lesser Scaup claims in Britain have proven problematical: a female (with a male) on Scilly one October in the late 90's looked very good for female Lesser Scaup, until the upperwing pattern was observed - a pattern very similar to the Derbyshire bird. The Scilly bird has yet to be submitted, but there are rumours that such a wing pattern may occur on Lesser Scaup anyway.

The Swarkestone bird was found on the late afternoon of Sunday 19th January 2003 by two local birders at Barrow GP. Tony Davison and and two other birders later re-located the bird on Swarkestone GP on Monday 20th and watched it for forty-five minutes before having to leave the bird for work commitments.

Tony takes up the story. "The bird was viewed at some distance in poor weather. First impressions were that although looking slightly larger than Tufted Duck, on size, head shape, bill pattern and general appearance, it looked okay and so was put out on the lines as a possible Lesser Scaup. During the time I viewed the bird on Monday and Tuesday morning, I never saw any wing pattern and on both occassions the bird was observed at a distance. A number of birders during the week watched the bird and claimed that the upper and underwing was okay. Doubts however crept in mid-week - in particular that a hybrid could not be ruled out.

I re-visited the site on Saturday and Sunday (25th-26th January) taking a large number of photos. I viewed the bird in better light and also at much closer range. I had nagging doubts about the overall size and structure, head shape, bill structure, nail and wing pattern in particular."

One of the best responses to the images posted in the surfbirds galleries has been sent to the surfbirdsnews discussion area by Martin Garner, and I hope he won't mind them being repeated here. Martin's comments conclude that he believes the bird to be indeterminate at the moment, though likely not a Lesser Scaup. Martin Garner comments

"Like some others I can only comment on the images, as I have not yet managed to see the Swarkstone bird ...thus the usual caveats about interpreting pictures without field experience of the bird etc. It is clearly proving be a fascinating and most educational individual. In my opinion......most of the key charactaristics look somewhat intermediate between a Lesser Scaup and (Greater) Scaup. Specifically:

Head shape: As others have mentioned the head shape looks too bulky and rounded for Lesser, though obviously the little peaked effect is not right for typical Greater.

Bill: I am not confident enough in the images, for nail details, but it doesn't feel like the typical shape/size (in relation to head) of Lesser.

Upperwing pattern: In the images on the Derby birder website of the upperwing I can see probably 5 outer primaries well spread out and I think white reaches possibly to p6 and at least to p5 ( I can't be 100% sure which feather is involved though I think it is p6 - based on length and shape of part opened wing). Importantly all of the bunched inner primaries appear to have obvious white on them - this is the typical pattern of many Tufted Duck and not far off the Greater Scaup upperwing photograph alongside. The white on primaries is normally a little duller than on secondaries in all these Aythyas. Is there any concrete evidence that female Lesser Scaup really has white on all the inner primaries to p5 or p6?

Underwing pattern: Useful reference photo's of the wings of Greater and Lesser Scaup are at the following sites:
http://www.npwrc.usgs.gov/resource/tools/duckplum/duckplum.htm http://www.ups.edu/biology/museum/wingphotos.html

Rob Fray's very helpful image on the Surfbirds rarity page shows white 'wing lining' contrasting with some grey on wing coverts but (and be aware the light is very harsh) the white 'showing through', which would represent the white secondary bar of the upperwing looks far too obvious for the Lesser Scaup pattern - perhaps this could be checked in the field.

Roughly speaking, in female Lesser Scaup, normally (as in Iain Leach's great photo in Birding World vol. 15: 12, page 506), the greater underwing coverts are grey so the whole underwing apart from small underwing coverts (white wing lining) looks grey - the white from the secondary bar is inconspicuous at best. In Greater Scaup the greater underwing coverts are white and the secondary bar 'shines through' as it does in Tufted and seems to do on the Swarkestone bird. Such differences in apparent visibility of white secondary bar shining through to the underside may also be a result on differing pigmentation on upper and under surfaces of secondary feathers in the different aythyas. I have not looked into such detail.

I don't think the bird can be called a Lesser Scaup. Maybe some of these thoughts can be further field tested on the bird. Thanks to the Derby birders for finding and creating discussion space for such an interesting bird."

Also on the surfbirds discussion forum, Carl Baggott says,

"It is interesting to see different people's perception of the probable female Lesser Scaup in Derbyshire. I believe that the photos show the bird to have the black restricted to the nail on the bill, and the crown to be peaked slightly towards the rear. Many photographs of acceptable Lesser Scaups show no peak to the crown.

All of the photos I have seen on surfbirds appear to be taken in poor light and have probably been edited and cropped to get the best quality image. My photo beefs the bird up to how it appeared to me in the flesh, and so do Rob's, in my opinion. I took other photos in good light the next day, and the structure appeared less bulky to me. I did not see the bird with its wings out stretched, but I did feel that the slightly concave bill profile, the faint ear patch, the extent of the white face patch, and the general plumage seemed to favour Lesser Scaup.

I do know that some Derbyshire birders put a lot of time in on this bird, and concluded that it was a Lesser Scaup after seeing the open wings etc. Apparently the wing pattern was not quite typical, but fell within the known variation. If it is a hybrid it is worrying, as how many other hybrids are mimicking so closely pure birds? It is certainly an interesting bird."

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