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Double-crested Cormorant
last update: Mar 24, 2009 02:22 PM
Latin name: Phalacrocorax auritus
Population: 1.2-2.2 million individuals
Cites classified: Least Concern
Where found: North America from the Aleutian Islands to Florida and Mexico
Age/ life expectancy: 6 years on average in the wild
Wingspan: 114-123 cm
Length: 70-90 cm
Weight: 1.2-2.5 kg
Mating/Breeding: Breeding occurs in coastal areas as well as near inland rivers and lakes. They build stick nests in trees, on cliff edges, or on the ground on suitable islands. They are gregarious birds usually found in colonies, often with other aquatic birds, and have a deep, guttural grunt call.
Eggs: 3-4 eggs, unmarked pale blue
Hibernation: winters along both coasts of the United States and at inland sites along large rivers and lakes southward of Indiana, USA
Aggressive: When threatened by a predator, gulls may threaten the predator or vomit fish at them. If the predator is large, the adults usually leave the nest, and circle overhead.
Hunting Habits: dives underwater
Feed on: fish mainly, but also amphibians and crustaceans
Predators: gulls, crows and jays, and grackles prey on eggs and chicks while bald eagles, great horned owls, caiman, and brown pelicans prey on adults and chicks
Colour/Body: The Double-crested Cormorant is a large waterbird with a stocky body, long neck, medium-sized tail, webbed feet and a medium sized hooked bill. This species has dark-colored plumage with bare super-loral skin and gular skin that is yellow or orange. An adult in breeding plumage will be mostly black with the back and coverts being a dark grayish towards the center. Nuptial crests, for which the species is named, are either white, black or a mix of the two. These are located just above the eyes with the bare skin on the face of a breeding adult being orange. A non-breeding adult will lack the crests and have more yellowish skin around the face. The bill of the adult is dark-colored.
Subspecies: P. a. albociliatus, Farallon Cormorant, breeds along the Pacific coast of North America from British Columbia to Bird Island in the state of Sinaloa, Mexico and possibly even further south; P. a. auritus has the largest and most widespread breeding population. It ranges from the Great Basin and Rocky Mountains east into central and eastern North America; P. a. cincinnatus, White-crested Cormorant, is the most restricted subspecies, geographically, and it has the smallest population of Double-crested Cormorant subspecies. It is found along the southern coast of Alaska and on the Aleutian Islands, ranging west from Kodiak to Chuginidak in the Aleutians; P. a. floridanus, Florida Cormorant, the smallest of the subspecies, it is found from southern and central Texas east to the Atlantic and from North Carolina south to Florida
Interesting Trivia:
- Large pebbles are occasionally found in cormorant nests, and the cormorants treat them as eggs.
- In breeding colonies where the nests are placed on the ground, young cormorants leave their nests and congregate into groups with other youngsters (creches). They return to their own nests to be fed.
- The Double-crested Cormorant swims low in the water, often with just its neck and head visible, and dives from the surface. It uses its feet for propulsion and is able to dive to a depth of 1.5–7.5 m. After diving, it spends long periods standing with its wings outstretched to allow them to dry, since they are not fully waterproofed.
