Thick-billed guillemots are one of the most numerous birds of the Arctic coast, moving southwards in the winter where the waters remain ice-free. They breed in large, noisy colonies, with each female laying a single egg on a narrow cliff ledge. In pursuit of a meal, thick-billed guillemots perform short shallow dives, but they are more than capable of reaching depths of 100m or more to reach favoured fish and squid.

At a glance it is difficult to distinguish these guillemots from closely related common guillemots. Their bills, as you would expect, are thicker and shorter with a white gape and they can also be darker in colour. The thick-billed guillemot is also known as Brünnich's guillemot after the Danish zoologist.

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