great scaup or lesser scaup (1 Viewer)

Dear forum colleagues

Please can anyone advise about the attached photo.
They were seen by many including experienced birders in NW England and positively identified as a great scaup .

Of course it has to be a great scaup on that basis.

As an inexperienced birder I am enquiring - theoretically speaking, how can we positively eliminate lesser scaup. What can we see in this photo that eliminates lesser scaup please?

Greater's head is smoother, and sometimes has a greenish tint.

There appear to be Greater and Lesser Scaup in this photo. The Greater on the right has a very steep forehead that curves abruptly as the forehead transitions to the bill, meanwhile the Lesser Scaup in the center in the foreground has a very gradual slope to the forehead. The bird in the back is probably a Greater Scaup as well. On Greater Scaup also note that there is usually a hump/peak on the front of the crown, in Lesser Scaup this is hump/peak is located towards the rear of the crown, but the hump/peak is not always evident in the field with either species.

greater and lesser scaup

Dear Tom
Thank you for your kind reply.
About there being a lesser scaup in this photo - are you sure?
In the UK, where this photo was taken, the lesser scaup is an extremely rare bird.
With kind regards, Ian

All look like Greater Scaup to me.

kasfig said:

Dear forum colleagues

Please can anyone advise about the attached photo.
They were seen by many including experienced birders in NW England and positively identified as a great scaup .

Of course it has to be a great scaup on that basis.

As an inexperienced birder I am enquiring - theoretically speaking, how can we positively eliminate lesser scaup. What can we see in this photo that eliminates lesser scaup please?

Click to expand...

To be honest, you can't positively eliminate Lesser Scaup from this photo - its quality isn't good enough. I'd assume the identities of these birds were established earlier by others because they'd been able to get closer views and/or better pics before you arrived.

Details you need to look for are the exact head shape (ideally averaged out from a set of photos showing the bird active / resting, wet / dry, etc.), the texture of the pattern in the grey on the back (whether fine [=Greater] or coarse [=Lesser], but burnt out by overexposure in your pic), the size of the 'nail' at the tip of the bill, and the extent of white in the wingbar when it has its wings open (wingbar white along full length = Greater, white on secondaries, grey on primaries = Lesser).

Hope this helps!