Black guillemot, Cepphus grylle.

Black Guillemot, Cepphus grylle

The black guillemot is a pigeon-sized sea bird. Like the rest of its family, its feet are placed extremely far back on its body to allow it to swim and dive better. In fact, it is an excellent swimmer and dives up to 40-m deep in pursuit of the small fish that make up its diet. When on land, it sits straight upright on its bright red feet. The rest of the black guillemot's body, including its eyes and bill, is black, interrupted only by a large white patch on each wing. In winter, the underparts are white and the upper parts are black speckled by white feather-tips.

Like many alcids, the black guillemot comes ashore from the ocean only to breed. When it does so, it chooses nesting sites on small cliffs, rocky slopes or beaches above the high tide mark. Unlike many marine birds, black guillemots are not entirely colonial – although colonies in the far north may include up to 10,000 birds, single pairs or small groups are also common. Pairs of guillemots do not build a complex nest, but perhaps dig a burrow in a soft sand or gravel bank, or assemble a few small pieces of gravel on which to lay their eggs. Eggs are often laid under the protection of overhanging vegetation, boulders or logs. Females lay one or, more usually, two eggs, which are green, buffy or white with brown and purplish-grey splotches. Males and females alternate incubating the eggs for a total of 4 weeks.

Black guillemots are circumpolar, and breed in Canada throughout the eastern Arctic and Atlantic coastal zones, including the shores of Baffin and Ellesmere islands. There is also a small, isolated breeding population in the far western Arctic near Alaska. In winter, the guillemots move south only as far as is necessary in order to find ice-free water. During this period they remain offshore, swimming and diving around the edges of pack ice.