What is happening to the tail feathers?

[photog46]

I saw this surf scoter April 1st at Scarborough Marsh in Maine.  It was surprising to me to see it there since I associate these birds with open ocean water, but I am new to Maine (and a not-too-experienced birder) and don't have much knowledge of the range of various species.  I noticed that there are bare shafts in the tail feather area.  In February, I submitted a photo of an eider with similar bare shafts (but on the wings), and responders suggested it was  condition called Angel Wing that can afflict birds that consume food that is not healthy for them.  Is this surf scoter suffering from a similar condition, or is this a natural phenomenon?  Could the issue have anything to do with the bird hanging out in a salt marsh all by itself instead of being part of a larger group on the ocean?  Thanks for your help.

[Quiscalus quiscula]

I'm not sure, it just looks worn though.

[Charlie Spencer]

Could have been lost in a near-miss attack.

[photog46]

Thanks to both for your thoughts.  I'm glad it didn't look to either of you like the Angel Wing issue, so I hope the bird was able to manage without the feathers.

[aveschapinas]

It looks a little bit scruffy, and I see some lines on the wing (just below the back of the neck) and back that look like they might be pin feathers; could this be molting?

[DLecy]

I'm no expert in SUSC molt, but it appears that this is an immature (1 CY) male undergoing Preformative Molt, which occurs on the wintering grounds.