Guillemots are the most common auk found in the British Isles. During spring these perky seabirds gather in massive and tightly packed breeding colonies, known as loomeries, on coastal cliffs and rock stacks. The females lay a single egg directly on a ledge. This might seem precarious, but their eggs are conical to prevent them rolling off the edge. When the chicks are three weeks old they have to take a dramatic plunge from their rocky shelf into the ocean below. Guillemots are also commonly called murres after the deep murmurings made by groups of nesting and fishing birds.

More...