Common guillemot

Guillemots are 38-45 cm in size. They nest in colonies on cliff edges. Thie eggs are pear-shaped so they don´t roll off (and I wonder if what is seen on the back of several birds in the third picture are eggs!).
The bridled form has a white ring round the eye, which looks like a pair of spectacles (you can see some of them like this if you look closely).
The spectacles like form is not a distinct subspecies, but a polymorphism that becomes more common the farther north the birds breed.