The Black Guillemot (Cepphus grylle) is a medium-sized auk of the rocky skerries, 30–32 cm long with a wingspan of about 52–58 cm and a weight of 400–500 grams. In summer plumage it is entirely sooty black except for a large, pure white wing patch, with bright red legs and — visible when it gapes — an equally bright red mouth lining; the bill is narrow, pointed and black. In winter the appearance changes dramatically to mostly white with a grey-speckled back, though the white wing patch remains, and the bird flies low over the water on fast, whirring wingbeats.
Black Guillemots breed in archipelagos along almost the entire Swedish coast, from Bohuslän through the Baltic to the Bottenviken, and are numerous around Stockholm, Bohuslän, Gotland and Åland, with a total population in the tens of thousands of pairs; the species is classed as Least Concern (LC). Unlike most other Swedish auks it is highly sedentary, remaining in its archipelago waters or nearby ice-free areas even through winter, and it breeds alone or in very loose groups rather than the dense colonies formed by Common Guillemots and Razorbills. The nest is hidden in a rock crevice, under a boulder or in a cliff crack near the water, and the female lays two eggs — unlike Sweden's other auks, which lay only one — incubated by both parents for around four weeks before the chicks are fed in the nest until fledged. It feeds on bottom-dwelling fish such as eelpout, goby and sandeel, plus crustaceans, diving to depths often between 20 and 50 metres and effectively "flying" underwater on its wings. Its call is a very high, thin, piping "tsii-tsii-tsii," heard mainly during courtship display at the nest hole.
Read about this species in Swedish →