Double-crested Cormorant

Double-crested Cormorant, adult non-breeding plumage, Everglades FL, January 1998

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Double-crested Cormorant , adult breeding

Double-crested Cormorant juvenile

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1. Description
2. Sound
3. Conservation Status
4. Other Names
5. Cool Facts
6. Full detailed species account

The Double-crested Cormorant is the most numerous and widespread North American cormorant. It's also the only one that occurs in large numbers inland as well as on the coast. Growing in numbers throughout its range, this cormorant is increasingly being blamed for declines in sport fisheries and for devastating fish farms.

Description

• Large, dark water bird.
• Long body and long neck.
• Medium-sized bill is blunt or hooked at tip.

• Size: 70-90 cm (28-35 in)
• Wingspan: 114-123 cm (45-48 in)
• Weight: 1200-2500 g (42.36-88.25 ounces)

Sex Differences

Sexes alike.

Sound

Deep guttural grunts.

Conservation Status

Cormorant populations greatly decreased in the 19th and early 20th centuries from human persecution. They recovered after the 1920s, with an interruption in the recovery during the pesticide era of the 1950s and 1960s. The National Audubon Society considered it a species of special concern in 1972. Increases after the 1970s were explosive in some areas. Increasing cormorant populations have caused conflicts with people. Cormorants have been suggested as playing an important role in the collapse of some fisheries, although data to support these claims are sparse. Cormorants eat fish at fish farms, and recent legislation has been proposed to control cormorant numbers. For more information, click here.

Other Names

Cormoran à aigrettes (French)
Cormorán Orejudo, Cormorán Bicrestado, Corúa de Mar (Spanish)

Cool Facts

• The Double-crested Cormorant makes a bulky nest of sticks and other materials. It frequently picks up junk, such as rope, deflated balloons, fishnet, and plastic debris to incorporate into the nest. Parts of dead birds are commonly used too.

• Large pebbles are occasionally found in cormorant nests, and the cormorants treat them as eggs.

• Double-crested Cormorant nests often are exposed to direct sun. Adults shade the chicks and also bring them water, pouring it from their mouths into those of the chicks.

• 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.

• Accumulated fecal matter below nests can kill the nest trees. When this happens, the cormorants may move to a new area or they may simply shift to nesting on the ground.

Sources used to construct this page:

Hatch, J. J., and D. V. Weseloh. 1999. Double-crested Cormorant (Phalacrocorax auritus). In The Birds of North America, No. 441 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.