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Great Cormorant

Status Fairly common resident. Breeds. Great Cormorants are common in summer along the coast but only in the region of their breeding rookeries, most of which are on eastern Cape Breton Island; elsewhere they are uncommon to rare. Fall migration to the south begins in September and reaches a peak in late October and early November. A substantial part of the population winters off New England. Remaining winter birds are seldom seen far from their established roosts on rocky ledges along the coast. The migratory birds return from mid-March onwards.

Description Length: 80-101 cm. All plumages: Bill 6.3-7.6 cm., hooked at the tip; tail with 14 feathers; feet black and fully webbed. Adults in breeding plumage: Body looks black with a bluish or greenish gloss; back feathers bronze-gray with dark borders; numerous hair-like feathers scattered over the head and neck; throat pouch yellow with wide, white hind border; patch of white on each flank, developed by early March and shed during May. Adults in winter: Similar but without the hair-like feathers on head and neck and without flank patches. Immatures: Sooty brown with whitish brown breast and belly.

Breeding Nest: In colonies on cliff ledges on islands or the mainland. Composed of twigs and other coarse vegetable matter, usually including fresh seaweed; sometimes composed entirely of seaweed. Eggs: 3-7, usually 4-5; bluish white, overlaid with a chalky deposit.

Laying begins during the latter part of April. Colonies of this cormorant in Nova Scotia are believed to have been established relatively recently. The first observed colony was at Crystal Cliffs, Antigonish County, where in June 1940 H.S. Peters found about 60 pairs nesting; by 12 May 1944 the colony had some 80 pairs. On 18 June 1940, I visited Bird Islands, Victoria County, and made a count of 39 occupied nests of this cormorant. A small colony I visited at Monk's Head, on the south side of Antigonish Harbour, had about 60 pairs, all appearing to be of this species; I was told by a local farmer that the colony was of very recent origin. Harrison F. Lewis visited Monk's Head on 11 June 1966 and found that the Great Cormorant colony there had ceased to exist because of erosion of the site by the sea. A Canadian Wildlife Service survey in 1971 (Lock and Ross 1973) estimated some 398 pairs of Great Cormorants on Bird Islands but only 33 pairs at Crystal Cliffs; the total population breeding in Nova Scotia was put at some 2,000 pairs out of a total Canadian population of about 2,700 pairs. The Nova Scotian population had increased about 1.5 times by 1982 (Milton and Austin-Smith 1983).

Range In North America, breeds locally in the Gulf of St. Lawrence, southern Newfoundland and along the Atlantic coast of Nova Scotia; most common in Cape Breton Island. Found as far south as North Carolina in winter. Other populations breed in western Greenland; the eastern North Atlantic from Iceland to the Cape Verdes; Eurasia; and Australasia.

Remarks Cormorants usually swim with their bodies submerged and only their head and neck visible I have never seen one swim with its lower back and tail above the water line. When I visited the Crystal Cliffs colony on 12 May 1944, the birds were losing their hair-like flank patches, wisps of which were lodged in the grass along the edge of the cliff; some birds had completely lost this adornment, and others retained only traces of it.

Over short distances, cormorants fly low and often in line, one behind the other, but during prolonged flights they often fly rapidly at considerable heights in V formation and are frequently mistaken for wild geese, which have a similar wing motion. In other parts of its range, the Great Cormorant breeds and winters on both inland and coastal waters. However, the North American population appears to make little use of freshwater habitats.