The bill please!

Razorbills are nesting in their usual cracks and crevices, separate but together with their own and other species.

Like puffins they develop exaggerated beaks prior to the breeding season but whereas puffins seem comical with those colourful stripey affairs, mature razorbills of both sexes wield lethal-looking weapons in stark black and white. 

The characteristic stripe is only acquired in the bird's second year (and sometimes there is another as well);  in addition the bill grows a thick aquiline ridge of bony reinforcement along the top. This and other specialised adaptations are crucial for successful breeding because these birds feed their young by catching small fish which they can collect up in batches along their beaks before returning to the nest. To catch just one at a time would be a futile expenditure of energy.  It goes without saying that the birds with biggest, boniest beaks are the most successful in the mating selection stakes - they have the best chance of rearing their (single) chick. Once the breeding season is over the beak resumes more modest proportions until the following year - if the bird survives.

I've been curious to find out about the bill and so was delighted to find a full description of the anatomy  with detailed illustrations here in the website of an artist, Rafael Galvez,  who specialises in drawing birds in the wild. It's an outstanding resource that I shall certainly return to - his skill and knowledge are incredible. He explains that a dead razorbill was found during the Christmas bird count in the Florida Keys and he did the drawings overnight by the light of a flash lamp before surrendering the specimen for freezing and removal to a research facilty. Impressive!

Extra: the beak enlarged. You can just about see how how capacious it can be, enough to stash a dozen or so small fish in a row.