Guillemot is the common name for various auk-type seabirds (Charadriiformes). In the UK there are two genera: Uria and Cepphus. This photos shows a guillemot at RSPB Bempton Cliffs on the coast of the East Riding of Yorkshire. If I told you that there is a species of guillemot known as the spectacled guillemot, you might imagine that this is she. However, this is actually a bridled guillemot. It’s not a distinct species but a genetic polymorphism of Uria aalge, the common guillemot (aka the common murre). This strain has thin white circles around its eyes that stretch back as a thin white line. By contrast the spectacled guillemot is rather distinct looking and has thick white circling around its eyes and no “bridle” and is Cepphus carbo.