Measurements
Both Sexes
- Length
- 27.6–35.4 in
70–90 cm - Wingspan
- 44.9–48.4 in
114–123 cm - Weight
- 42.3–88.2 oz
1200–2500 g
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.
Habitat
Lake/Pond
Found in diverse aquatic habitats, such as ponds, lakes, rivers, lagoons, estuaries, and open coastline; more widespread in winter.
Food
Fish
Predominantly fish. Also some other aquatic animals, insects, and amphibians.
Nesting
Nesting Facts
- Clutch Size
- 1–7 eggs
- Egg Description
- Unmarked pale blue.
- Condition at Hatching
- Naked and helpless.
Nest Description
Large, often flat nest of sticks and other bulky items, including seaweed and flotsam. Lined with grass or similar material. Placed in trees, on ground, or on cliffs. Nests in colonies.
Nest Placement
Ground
Behavior
Surface Dive
Dives from the surface of the water and chases prey underwater. Grabs fish in bill, without spearing it.
Conservation
Least Concern
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.
Credits
- 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.