- 27.6–35.4 in
- 44.9–48.4 in
- 42.3–88.2 oz
- The size of a small goose; larger than Neotropic Cormorant, but smaller than Great Cormorant.
- Cormoran à aigrettes (French)
- Cormorán Orejudo, Cormorán Bicrestado, Corúa de Mar (Spanish)
- From a distance, Double-crested Cormorants are dark birds with snaky necks, but up-close they’re quite colorful—with orange-yellow skin on their face and throat, striking aquamarine eyes that sparkle like jewels, and a mouth that is bright blue on the inside.
- The double-crest of the Double-crested Cormorant is only visible on adults during breeding season. The crests are white in cormorants from Alaska, and black in other regions.
- Cormorants often stand in the sun with their wings spread out to dry. They have less preen oil than other birds, so their feathers can get soaked rather than shedding water like a duck’s. Though this seems like a problem for a bird that spends its life in water, wet feathers probably make it easier for cormorants to hunt underwater with agility and speed.
- 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.
- 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.
- The oldest known Double-crested Cormorant was more than 22 years old, banded in Ontario in 1984 and found in Louisiana in 2006.
Double-crested Cormorants are colonial waterbirds that seek aquatic bodies big enough to support their mostly fish diet. However, they may roost and form breeding colonies on smaller lagoons or ponds, and then fly up to 40 miles to a feeding area. In addition to fishing waters, cormorants need perching areas for the considerable amount of time they spend resting each day. After fishing, cormorants retire to high, airy perches to dry off and digest their meals—rocks, wires, tops of dead trees, ship masts. They tend to form breeding colonies in clusters of trees in or near water. After a while, masses of cormorant guano may kill these trees and the trees may topple, at which point the cormorants may switch to nesting on the ground.
A cormorant’s diet is almost all fish, with just a few insects, crustaceans, or amphibians. They eat a wide variety of fish (more than 250 species have been reported), and they have impressive fishing technique: diving and chasing fish underwater with powerful propulsion from webbed feet. The tip of a cormorant’s upper bill is shaped like a hook, which is helpful for catching prey. When cormorants happen to catch a crustacean like a crayfish, they exhibit a little flair in eating it—hammering the prey on the water to shake its legs off, then flipping it in the air and catching it headfirst for easy swallowing.
- Clutch Size
- 1–7 eggs
- Number of Broods
- 1-2 broods
- Egg Length
- 2.2–2.8 in
- Egg Width
- 1.4–1.6 in
- Incubation Period
- 25–28 days
- Nestling Period
- 21–28 days
- Egg Description
- Unmarked pale blue.
- Condition at Hatching
- Naked and feeble, eyes closed and barely able to move head.
Both Double-crested Cormorant mates work on the nest, with the male bringing most of the material and the female doing the building. The nest is mostly made of finger-size sticks, with some seaweed and flotsam, and lined with grass. Nests are 1.5 to 3 feet in diameter and 4 to 17 inches high; ground nests tend to be wider than tree nests, but tree nests have deeper interiors. Breeding cormorants readily steal nesting materials from a nearby nest that’s not guarded.
The male chooses the nest site and then attracts a female. Nests can be on the ground, on rocks or reefs with no vegetation, or atop trees, which may be alive when a cormorant colony first forms but typically die after a few years from the guano build-up. Nests are built in the center of a colony first, then expand outward.
Double-crested cormorants are gregarious birds that are almost always near water. Their main two activities are fishing and resting, with more than half their day spent on the latter. When at rest, a cormorant will choose an exposed spot on a bare branch or a windblown rock, and often spread its wings out, which is thought to be a means of drying their feathers after fishing. (Cormorants have less preen oil than other birds, so their feathers can get soaked rather than shedding water like a duck’s. Though this sounds like a liability, this is thought to be an adaptation that helps cormorants hunt underwater more effectively.) When swimming atop the water, cormorants ride very low, and often only their long necks are evident. Before a cormorant takes off in flight, it tends to stretch its neck in the direction it intends to fly. When it comes in for a landing, a cormorant will puff out the orange skin on its neck and, after touchdown, give a ritual little hop. If one cormorant encroaches on the space of another, such as in competition over a nest site, the cormorants will face off, stretch their necks, and open their mouths wide open to show off the blue color inside while shaking their heads and hissing at each other. To attract a mate for the season, a male cormorant will choose a nest site and then stand with his breast down and bill and tail up, showing off the crests on his head and bright colors of his neck and his eyes, grunting and slightly waving his outstretched wings. When a female arrives, she is greeted by the male opening his mouth into a gape, showing off the blue inside.
Double-crested Cormorant populations have rebounded from persecution and pesticides over the past couple centuries, and today they are a widespread and abundant species. In the 1800s and early 1900s, cormorants were frequently shot, and their numbers declined with westward settlement. They also suffered greatly from pesticides used in the mid-20th century, such as DDT, which cormorants ingested from the fish they ate. The pesticides caused thin eggshells. Since the 1970s, cormorant populations have grown steadily, even explosively. In the Great Lakes, some cormorant colonies have doubled in five years. Some people still regard cormorants as a threat to fishing stocks, and the U.S. Fish and Wildlife Service sometimes issues permits for controlled cormorant shooting to protect fisheries.
- 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 Online, Ithaca, New York.
- Dunne, P. 2006. Pete Dunne’s Essential Field Guide Companion. Houghton Mifflin, New York.
- Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.
- USGS Patuxent Wildlife Research Center. 2011. Longevity Records of North American Birds.
Resident to medium-distance migrant. Populations in the continental interior and northern Atlantic Coast migrate to the southern and southeastern U.S.; western populations migrate to the Pacific Coast; Florida, coastal Pacific Northwest, and coastal Mexican populations do not migrate.
Find This Bird
Look near lakes and coastlines for perched black waterbirds, smaller and with shorter legs than a heron, and a distinctive S-shaped crook in their neck. On the water they sit low, with the head and bill usually tilted slightly upward. You may also see them holding their wings spread-eagled and sunning themselves. Flocks of cormorants fly in irregularly shaped lines or sloppy V’s. In flight, cormorants hold their head up, neck slightly bent, belly hanging low, and their wing beats are slow and labored.