Black guillemot

The black guillemot, also known as the tystie, is a captivating medium-sized seabird belonging to the alcid family. These birds can be observed along the northern Atlantic coasts and the eastern shores of North America, with some migrating further south during the winter months. They are typically found around rocky shores, cliffs, and islands, usually in pairs or small groups. As proficient divers, black guillemots primarily feed on fish, crustaceans, and other small marine organisms.

Both male and female black guillemots exhibit similar appearances. During the summer, they display black plumage accented by a distinctive white wing patch, complemented by long black bills and bright coral-red feet. The breeding season extends from late February to early May, during which time they often form pairs or small groups. Each pair usually lays two eggs and raises two chicks, which fledge at around 30-40 days old. Once independent, the young birds typically rejoin their original colony.

The genus name "Cepphus" is derived from the Ancient Greek word "kepphos" while "grylle" is a local name for the bird in Gotland, as noted by Linnaeus. The English name "guillemot" likely originates from the French "guillemot" possibly rooted in "Guillaume" meaning "William."

Black guillemots have a wingspan ranging from 52-58 cm and weigh between 300-460 grams. They exhibit seasonal plumage changes, with no significant differences between males and females. Juveniles and immature birds can be identified by the spots on their white wing patches. These birds are distributed across the North Atlantic and Arctic Oceans, breeding in regions from 43° to 82°N.

Preferring rocky shores for nesting and foraging, black guillemots primarily feed on benthic prey near their colonies. Their diet consists of fish, crustaceans, mollusks, insects, and occasionally plant material. Various subspecies of black guillemots are distributed across North America, Europe, and Asia.