Double-crested Cormorant

Phalacrocorax auritus

Order: Suliformes / Family: Phalacrocoracidae

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black large waterbird wetland coastal migratory common widespread

About the Double-crested Cormorant

The Double-crested Cormorant (Phalacrocorax auritus) is a widespread waterbird found across North America, notable for its adaptability to various aquatic environments. This species is significant due to its role as both a predator and an indicator of water quality. Cormorants are often seen in large colonies along coastlines, lakes, and rivers, where they contribute to the ecosystem by controlling fish populations and influencing the structure of aquatic communities. During breeding season, their distinctive double crests, which are tufted feathers on their heads, become more pronounced in adults. These birds are highly social and often form large, noisy colonies. Throughout the year, the Double-crested Cormorant's behaviors and habitat preferences change slightly, adapting to seasonal variations. In the summer, they breed in colonies on rocky islands or dense tree stands near water, primarily in Canada and the northern United States. Come winter, many move to southern regions where they inhabit coastal bays and estuaries, although some remain year-round residents in milder climates. Their ecological role extends beyond predation, as their guano enriches soil fertility, benefiting plant growth in their nesting areas. Despite their benefits, Double-crested Cormorants sometimes face conflict with fisheries, as they are efficient hunters capable of significantly impacting fish stocks. This has led to discussions about their management and conservation in various regions.

The Double-crested Cormorant belongs to the family Phalacrocoracidae, within the order Suliformes. These birds typically live average lifespan of 6 years, with a maximum recorded of over 20 years..

How to Identify a Double-crested Cormorant

Adult Double-crested Cormorants are large, black waterbirds with a wingspan that can reach up to 52 inches. They are easily identified by their orange-yellow skin around the base of the bill and throat, contrasting with their dark plumage. The long neck and slender bill are characteristic, and during the breeding season, adults develop two small tufts of feathers on their heads, giving them their 'double-crested' name. Juvenile cormorants are browner, with paler underparts, and lack the distinctive crests of the adults. Males and females look similar, though males are slightly larger. In flight, their silhouette is distinctive; they hold their necks outstretched and their wings slightly bent, creating a cross-like shape. When perching, they often spread their wings to dry, a behavior that aids in identification. This posture, combined with their habit of sitting low in the water with just their necks and heads visible, helps differentiate them from similar species like the Great Cormorant, which is larger and has a bulkier build.

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Double-crested Cormorant Habitat and Range

Preferred Habitat

Double-crested Cormorants inhabit a variety of aquatic habitats, including freshwater lakes, rivers, coastal bays, and estuaries. They are commonly found at elevations from sea level up to 1,500 meters. During the breeding season, they prefer isolated islands or secluded shorelines with ample trees or rocky ledges for nesting. In winter, they shift towards coastal marine environments but can still be found inland along major water bodies. While they are more prevalent in rural and natural settings, these birds occasionally venture into urban areas, particularly those with large water bodies, where they can often be seen perching on man-made structures.

Geographic Range

The breeding range of the Double-crested Cormorant extends from Alaska across Canada to the Great Lakes and down through much of the United States. During winter, they migrate to the southern United States, Mexico, and Central America, although some populations remain along the Pacific and Atlantic coasts year-round. Key migration corridors include the Mississippi Flyway and the Atlantic seaboard. The highest population densities occur in the Great Lakes region and along the Gulf Coast. In recent decades, their range has expanded, and they are now seen more frequently in areas where they were previously rare.

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What Does the Double-crested Cormorant Eat?

The diet of the Double-crested Cormorant primarily consists of fish, which they catch through skilled underwater pursuit. They are opportunistic feeders, adapting their diet to available prey. Common fish species consumed include perch, sunfish, and catfish, with prey typically ranging from 5 to 15 inches in length. During the breeding season, when energy needs are higher, they may also consume crustaceans and amphibians. Cormorants usually forage during daylight hours, often in groups, which can enhance their fishing success. Their foraging strategy involves diving below the surface and using their webbed feet for propulsion, allowing them to maneuver quickly and capture prey efficiently.

Double-crested Cormorant Behavior and Social Structure

Double-crested Cormorants are highly social birds, often seen in large flocks during both feeding and roosting. They exhibit complex social structures within their colonies, where they establish loose territories around nesting sites. Courtship displays involve males presenting nesting material to females and performing a series of wing-spreading and vocalizations. These birds are excellent divers, using their webbed feet to propel themselves underwater in pursuit of fish. They are also known for their communal roosting behavior, often gathering in large numbers on trees or power lines near water bodies. In response to predators, cormorants rely on their ability to dive swiftly and take refuge in water. Their daily activities are generally synchronized with dawn and dusk, periods when they are most active.

Double-crested Cormorant Nesting and Reproduction

Nesting for the Double-crested Cormorant typically occurs in colonies, with nests built in trees or on the ground on rocky islands. Nests are constructed from sticks, seaweed, and other debris, often reinforced with their guano. Clutch size usually ranges from 3 to 4 eggs, which are incubated by both parents for about 28 to 30 days. After hatching, both parents are involved in feeding the chicks through regurgitation. Young cormorants fledge at approximately 5 to 6 weeks old but continue to depend on their parents for food until they are proficient hunters. Typically, they raise one brood per year, although some southern populations may manage two.

Double-crested Cormorant Sounds and Vocalizations

The Double-crested Cormorant is generally silent except during the breeding season when they produce a series of deep, guttural croaks and grunts. These vocalizations are often heard around colonies, especially during courtship displays. Their calls can be compared to the sound of a pig's grunt, lacking any melodic quality. Alarm calls are rare, but when disturbed, they emit a harsh, throaty noise to warn other cormorants. Unlike songbirds, they do not participate in a dawn chorus, and their sounds are more functional than musical.

Interesting Facts About the Double-crested Cormorant

1Double-crested Cormorants can dive as deep as 25 feet to catch fish, showcasing their remarkable adaptability.
2Their feathers are not completely waterproof, which aids in diving efficiency but requires them to dry their wings frequently.
3While considered a nuisance by some fishermen, they play a critical role in controlling invasive fish species populations.
4Cormorants can live up to 20 years in the wild, with some individuals being banded and tracked to study their movements.
5This species was nearly eradicated in parts of North America during the mid-20th century due to pesticide exposure.
6Unlike most birds, their bones are relatively heavy, which helps them stay submerged while hunting underwater.
7The distinctive orange skin of the Double-crested Cormorant becomes more vibrant during the breeding season.

Double-crested Cormorant Conservation Status

Currently, the Double-crested Cormorant is listed as Least Concern by the IUCN, with populations generally stable or increasing. However, they have faced significant challenges historically, including habitat destruction and persecution due to perceived competition with fisheries. Conservation efforts have focused on habitat protection and management plans to balance their presence with economic interests. Recent studies suggest that populations are rebounding, particularly in areas where wetland restoration has occurred.