The Razorbill nests in dense colonies on bird cliffs and rocky skerries, often together with the Common Guillemot. Unlike the Common Guillemot, which incubates its egg on open rock ledges, the Razorbill places its nest more sheltered in a rock crevice, a fissure or beneath a boulder. The female lays a single egg, and both parents incubate for about a month. The chick leaves the cliff before it is able to fly and makes its way out to sea together with the male, who continues to feed it.