Introduction The double-crested cormorant is the most numerous and widespread North American cormorant, although this bird is listed as a species of special concern by the California Department of Fish and Game. Owing to the isolation of Channel Islands National Park, this bird is provided with the protected breeding area of Santa Barbara Island, and especially Prince Island off the northeast coast and Castle Rock off the northwest coast of San Miguel Island. Anacapa Island also has established breeding colonies.
Quick and Cool Facts
Double-crested cormorants are the most numerous and widely distributed species of the six North American cormorants.
Their range extends from the Aleutian Islands in Alaska down to Mexico.
Like other cormorants, their feathers are not waterproof and they need to dry their wings after spending time in the water.
During the breeding season, the skin on their throat turns bright orange.
Double-crested cormorants nest in a variety of places: on the ground, cliff edges, trees, shrubs, and in artificial structures.
Double-crested cormorants make a bulky nest of sticks and other material. They 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.
Females on average lay four eggs. Large pebbles are occasionally found in cormorant nests, and the cormorants treat them as eggs.
Incubating adults hold the eggs on their feet.
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.
They are gregarious birds usually found in colonies. 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.
Appearance Double-crested cormorants weigh from 3.3 to 6.6 pounds and measure 33 inches in length, with a wingspan of about four feet. Sexes look similar, with short, dark legs, a long black body and neck; a lighter colored bill with a hooked tip, bare orange skin around the face and chin. Breeding adults have brilliant turquoise eyes and mouth lining. A small curled plume on either side of the crown may be seen during the breeding season. The long neck is kinked in flight. Because their feathers are not waterproof, double-crested cormorants often spread their soaked wings out to dry after a dive. This incomplete waterproofing helps reduce buoyancy, a valuable attribute for a diving seabird.
Range Growing in numbers throughout its range, the double-crested cormorant is widely distributed across North America. It breeds locally along all coasts and extensively in Florida, the center of continent, and along the Great Lakes and the St. Lawrence Seaway, as well as in Mexico, Belize, the Bahamas, and Cuba. Most cormorants winter along the Pacific Coast from Alaska to Mexico, along the Atlantic and Gulf coasts from North Carolina to Belize, and inland on ice-free areas along large rivers and lakes.
Habitat The double-crested cormorant is very adaptable. They may be found in diverse aquatic habitats, ranging from rocky northern coasts to mangrove swamps, lagoons, estuaries, rivers, small inland ponds, and large reservoirs. The double-crested cormorant is a species that is even more widespread in winter. The largest number of colonies in southern California of double-crested cormorants is found on islands of Channel Islands National Park with nesting occurring on Santa Barbara, Anacapa, and San Miguel islands, with an occasional colony on Santa Cruz Island.
Feeding The diet of the double-crested cormorant consists predominantly of a wide variety of fish. The cormorant dives from the surface and chases fish underwater, propelled by its powerful webbed feet. The bird then grabs the fish with its bill, rather than spearing it; upon surfacing, it flips the fish into the air, then catches and swallows it head-first.
Reproduction They first breed at 3 years of age in nesting colonies, sometimes with other wading birds. The birds make a bulky nest of sticks and other bulky items, including seaweed and flotsam, often lined with grass in a tree near water, on a cliff ledge, or on a beach. They frequently pick up debris, including rope, deflated balloons, and fish nets, to incorporate into the nest. The cormorants usually lay 3 to 4 pale blue eggs. Cormorant hatchlings are naked and helpless. Both parents care for the chicks. Double-crested cormorant adults shade the chicks and bring them water, pouring it into the chicks' mouths from their own. In ground-nesting colonies, young cormorants leave their nests and congregate with other youngsters, called crèches, returning to their own nests only to be fed. The young birds begin to fly at about 5 weeks, and become independent at about 9 weeks of age.
Migration Populations on the west coast generally are permanent residents, but double-crested cormorants elsewhere are migratory. They migrate by day in flocks, often forming "V"-shaped formations as they follow rivers or coastlines, headed from the coldest parts of their breeding range toward ice-free areas.
Conservation Status Although, the double-crested cormorant is a wide spread species and classified as Least Concern on the IUCN Red List, in 2002 the California Department of Fish and Game listed the double-crested cormorant as a species of special concern. This variance occurred due to the fact that the bird is not listed under the federal Endangered Species Act or the California Endangered Species Act. Due to the fact that human threats and climatic conditions produced low historical populations, it made it prudent to take a conservative view to the species. In California, Channel Islands National Park, as well as refuges and ecological reserves, are protected areas for this bird.