Double-crested cormorants have long, thin necks and a large, rounded, orange throat pouch. Adults are black while immature birds are light brown with pale throat and chest areas. Males and females are similar in appearance. They have a straight bill that is hooked at the tip. During the breeding season, adults develop a double crest of two tufts, generally white, curving back from behind their eyes. While wading, the cormorant has such a low profile it may look like a periscope sticking up out of the water. They are usually silent, except for pig-like grunting calls in the nesting colony. They reach a length of 29 to 36 inches with a wingspread of 54 inches. Usually, they weigh around 4 to 4.25 pounds but can grow to over six pounds. Double-crested cormorants are often seen perched with their wings spread out. To reduce buoyancy for diving, cormorants lack waterproofing oils. After fishing, the cormorant must hold its wings open in the sun and breeze to dry. Other names for the double-breasted cormorant are: crow-duck, Farallon (Pacific Coast) cormorant, Florida (South) cormorant, lawyer, white-crested cormorant and Taunton turkey (New England).
Range: They have the widest range and greatest adaptability to habitat of any North American cormorant. They are the only species found in the interior of the North American continent. Cormorants are generally found on lakes and reservoirs in eastern Colorado in the summer. A few have been documented at higher elevations including some at MacFarlane Reservoir in North Park, Antero Reservoir in South Park and Eastdale Reservoir in the San Luis Valley. Most birds migrate to Texas or Mexico, but a few remain in Colorado in winter.
Habitat: They breed on islands along the coast and around deep, inland lakes where fish are abundant. They generally require trees for nesting but do well on treeless islands such as those in the Gulf of California.
Diet: Double-crested cormorants dive and swim around in pursuit of prey, generally to depths of five to 25 feet below the water’s surface. They usually stay under less than 30 seconds but can stay submerged up to 70 seconds. Their diet consists of fish, salamanders, spider crabs, shrimp, crayfish, some reptiles, mollusks and sea worms.
Reproduction: Double-crested cormorants build large, shallow nests on the ground or in trees. The male and female both participate, and it takes an average of four days to build the nest. The male builds the foundation, and he will bring material in for the female to continue building. The male will add material to the nest throughout the season. Old nests are often rebuilt, and the same nest may be used for at least four years. When they are built in trees, nests are constructed out of twigs, roots, weeds, vines, and plant debris; on the ground and rocks, seaweed and trash are used. It has been found that some nests incorporate pocket combs, feathers, pocketknives, hairpins and men’s pipes. The female will lay two to seven chalky-blue eggs between April and July, and both parents will take turns incubating them for 24 to 25 days. The young are fed regurgitated food by reaching into the parent’s gullet or by picking up disgorged food. When they are three to four weeks of age, the young wander from the nest, gather in bands, and move through the entire colony to socialize.
For more information, see the Natural Diversity Information Source species profile.