Razorbills nest in colonies in remote, sheltered holes and crevices in cliffs, among boulders on rocky foreshores; sometimes they choose a puffin hole but only very rarely use exposed ledges chosen by guillemots.
The birds arrive at their colonies from the end of January onwards, but breeding begins in earnest in April. No real nest is made, except sometimes a few plants or stones are used. A courting pair may be seen in the so-called 'ecstatic' pose, where one bird stretches its beak up into the air, making a grating noise with bill parted, while its mate nibbles its throat.
A single egg is laid from early May onwards and both parents incubate it for 33 - 36 days, then share the feeding duties. At about 18 days old, the still down-covered chick launches itself from the cliff, fluttering down on tiny wings, usually at night to avoid predatory gulls. They often fall onto rocks or into heavy surf but they are well protected by fat and feathers and can swim strongly. Their parents continue to feed them out at sea until they can fly and fend for themselves.Read More: Razorbills and Humans