Scaup I.D. please

[Kris Ito]

Ugh, I thought this fellow might be a Lesser Scaup because of his peaked head shape, but now I'm not so sure...
Scaup i.d. by Kris Ito, on Flickr

[thouc]

This one is tricky. The greenish sheen on the head would point towards Greater. Greater should however have a rounded shape of the head with the highest point in front of the eye. The peak of the lesser is at the back of the head. The peak of this bird is right behind the eye, which is intermediate between Lesser and Greater. The black on the bill seems to cover more than just the tip of the bill, which points towards Greater.

In conclusion I would say it is probably a Greater Scaup, but I wouldn't rule out a hybrid Greater x Lesser Scaup, which should occur, but I haven't been able to find any information about it. I guess because of the similarity between the parent birds it is difficult to identify.

Do you have any more pictures of this bird?

/Thomas

[Reuven_M]

Definitely Greater Scaup for me. Saying that the peak is in front of the eye on greater is essentially just an easy way to explain the different head shape - which is perfect for greater in this picture, despite the peak being slightly further back. This bird shows a very smoothly rounded head shape. I think the shadow is making it look a bit different. This site has a couple good comparisons: http://www.utahbirds.org/featarts/Scaup.htm
Lessers look small-headed, with a more forward-placed eye and a very distinct angle on the back of the head. Lessers can look more like Greaters when actively diving, but Greater will never show the head shape of Lesser.
Greater Scaup vastly outnumber Lessers in mid-winter in our area. If you're having trouble picking out any Lessers, it may be that none are present! The combination of size, head shape and (usually) head colour mean Lessers are quite obvious when among a flock of Greaters.

[thouc]

When looking at the picture again I think the peaked appearance is an illusion caused by the dark wave behind the head. So, as Reuven said, definitely Greater Scaup.

/Thomas