The Pelagic cormorant of the Pacific Coast is a cormorant that is small and slender, and exclusively marine in habits, but preferring inshore areas. It is black, and its body has a glossy iridescent green with violet-bronze, and violet-purple on its neck. The breeding plumage includes white patches on the flank, red skin at the base of the bill, two head crests, and long white feathers on the neck and upper-back. This species may be solitary when feeding but gregarious during other times, when groups perch together on rocks near the water, holding their wings out to dry. Often they are shyer than other cormorants and harder to approach.
Pelagic cormorants inhabit the Bering and Chukchi Seas along the North American coastal Pacific area to Baja California and the Asian coast to south China. They breed on the North Pacific coasts (South West Alaska and North East Siberia), and winter south to Baja California, Japan and East China. These birds frequent rocky bays, and particularly deep waters near the base of cliffs. Nesting is both on mainland coasts and islands, often on inaccessible sites, such as steep slopes or narrow ledges on cliffs.
Pelagic cormorants forage only during the day and usually alone in sheltered bays and inlets. They usually swim until locating prey, and though preferring shallow waters, may dive to 180 feet (55 m) to on or near the floor of the sea, steering with their wings and propelled by their feet as they chase their prey under water. On emerging from the water, they perch in a dry area to spread their wings out to dry. These birds are very adept both swimming and flying and can jump straight out of the water and into the air. On land a Pelagic cormorant is quite clumsy and walks with a high-stepping, waddling gait. When landing, they usually scratch at the ground and when feeling threatened, they dart at their opponents with their bills, shaking their heads and making gargling noises. This species is often sedentary, but populations will sometimes perform a short post-breeding dispersal. Individuals make groaning and hissing calls in the colonies. Birds that are perching may make low-pitched moaning and clicking sounds.
Pelagic cormorants are serially monogamous and pairs remain together at least for one breeding season. During the breeding season, males try to attract females by displaying at the nest site with their bill pointed up, their tail down, rapidly raising and lowering the tips of their folded wings so that the white flank patches seem to flash rapidly. Laying takes place from May to July. These birds nest as isolated pairs or in small colonies, on inaccessible sites like narrow ledges or hollows in tall, steep cliffs and rocks. Both adults make the nest, from sticks, algae, moss, grass and debris, reusing it for several subsequent years, adding new material every year. 3-5 bluish-white eggs are laid, and become stained in the nest. Incubation is for one month, shared by both adults. When hatched, the parents feed the chicks, which make short flights when they are 35-40 days old. When they are 45 and 55 days old, they leave the nest, and depend on their parents for food for several more weeks. They reach reproductive maturity at about two years old.
This widespread and numerous species has a very extensive range and so is not considered threatened. But this species is vulnerable to contaminants such as oil pollution, may drown in the gill-nets of fisheries near their feeding areas, and is also affected by increasing recreational activities which cause disturbance at nesting sites.
According to the U.S. Fish and Wildlife Service (FWS) resource, the total breeding population size of the Pelagic cormorant is 400,000 birds, about one third of which is in North America, with 43,700 individuals in 420 colonies in Alaska. The IUCN Red List records the species’ national population as follows: in China: fewer than 100 breeding pairs, with 50-1,000 wintering individuals; in Korea: 100-10,000 breeding pairs, 50-1,000 migrating individuals and 50-1,000 wintering birds; in Japan: 10,000-100,000 breeding pairs, with 1,000-10,000 migrating individuals and 1,000-10,000 wintering birds; in Russia 10,000-100,000 breeding pairs, with 1,000-10,000 birds on migration. Overall, currently Pelagic cormorants are classified as Least Concern (LC) on the IUCN Red List but their numbers today are decreasing.