Stinky Bay on Benbecula is always worth a look if you can cope with the stench. Oodles of rotting seaweed create a strong smell, especially in summer, but also attract a host of birds feeding along the shoreline.
Eiders are a regular feature and at least one ‘Boreal’ Eider has shown up previously (spring 2010). Today I found another, or the same drake returning. Nice rich yellowy bill, extra wings/nipples/spurs/sails/fins (whatever you want to call them) protruding from its back, “English Mustard” coloured legs and feet and narrow black running down the sides of the bill lobes. The lobes too differed in shape from the other “Common” Eiders, so it ticked the boxes in terms of sub ‘specific identification.
Still a very rare bird, with a handful of British claims and work on going about admitting it to the national list, early spring in the Western Isles does seem to be a good time to find one.
Note the often referred to likeness of the bird to one of your ‘Grandma’s Fairy Cakes’ with the protruding sails. Elimination of Fairy Cakes on other features should be straightforward ie lack of yellow feet.