Hi Jan ,
I think it’s difficult to say anything useful based on these photos alone. I’m sure you’ll agree that the quality of both yours and Brian Wielsøe’s photos are rather poor , and bill shape and colour , size of knob on the bill , plumage colour and so on , looks decidedly different depending on which picture you’re looking at.
However , it could be interesting to hear why you guys – who have actually seen the bird – think it is a white-winged scoter , and also which race you suspect it to be. As you probably know , the breeding ranges of the nominate “race” (fusca) and the Siberian “race” (stejnegeri) meet at the Yenisey River , so maybe there's a possibility that it might be a hybrid between these two races/species as well?
I saw the bird yesterday and believe it to be a "deglandi". I agree with Jon that the photos are quite poor but I definately think it is possible to see several interesting features.
The bill colour is obviously more flesh-coloured (reddish) than the more yellow-billed "fusca". This was also one of the most obvious features when the bird was seen in the field. I have personally never seen that bill-colour on any "fusca".
The white markings around the eye was significantly larger than on the nearby "fuscas" (as seen on the photos). The shape of these markings were also different from "fusca" as the white proceeded above the eye - which again is visible on the photos.
The shape of (especially) the birds head was also different from fusca. The bird had a longer bill which gave it an Eider or Surf Scoter-like profile.
The knob on the bill was very difficult to see, but I think these pictures show the knob quite well http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=29848
I did not notice brownish flanks and I could not make out the exact markings on the birds bill. So I will (for the moment) not try to guess on the birds subspecific identity.
It is of course almost impossible to exclude possible hybridisation between the species, but if the bird does not show any obvious intermediate characters I see no reason to suspect hybridisation.
It should be mentioned that the same flock of scoters at the moment also holds a drake American Scoter (has been seen regularly here since 2003!). This presents a perfect opportunity for WP-twitchers to potentially catch up with a couple of very tricky ticks!
The site is also known as the best Danish site for Surf Scoter, but this species hasn't been seen here since 2006.
The scoters can be seen from a little icecream-shop along the road "Fyrvej" just 300 meters southwest of Blåvand Lighthouse (westernmost part of Denmark) about 100 km north of the German border.
It’s true that there is an obvious difference in the colour of the bill on some of the pictures. However , there are also some where the difference is harder to see – like on the background photo above , and indeed on most of BW’s photos where it only looks a bit darker yellowish – on my monitor anyway. The length of the bill also varies greatly depending on what photo you look at. This difference in appearance is especially obvious on BW’s leftmost photos (the bottom one showing a rather short bill) , where the shape of the head also looks very different from each other. That’s why I think that the birders having seen this bird in the flesh , is in a much better position to comment – which Sebastian has done nicely!
I agree , that there should be some intermediate character(s) indicating hybridisation , for this possibility to be considered. However , as Sebastian states , the knob on the bill seems to be a bit on the small side… - for stejnegeri anyway. This could point towards deglandi or possibly a fusca X stejnegeri hybrid , but again it’s not easy to decide from the photos alone , I think. YK also has an opinion regarding the bill pattern , maybe indicating a possible hybrid , in his comment on BW’s photos.
I think Sebastian is right regarding the white patch beneath the eye , which looks good for deglandi/stejnegeri. I could be interesting to hear if this bird showed the white patch on top of the bill which is normally quite easy to see on deglandi – as YK points out. It’s not visible on the photos , but maybe those who have seen the bird could comment on that? In my experience the brownish flanks can be a bit difficult to see , but good and prolonged views normally reveal it at some stage.
Height of bill 'knob' is considerably less important than overall head/ bill profile and bill colours. Both of these fit stejnegeri much better than deglandi on this bird. Indeed the bill knob can certainly be less tall with less of a protuberance on some stejnegeri, (perhaps younger males). So based on these slightly blurry photos it looks fine for Stejneger's Scoter.