Overview

Brief Summary

Phalacrocorax auritus

A large (33 inches) waterbird, the Double-crested Cormorant is most easily identified by its black body and wings, long hooked bill, and orange chin patch. This species may be separated from the related Great Cormorant ( Phalacrocorax carbo) by that species’ larger size and large white chin patch, from the related Neotropic Cormorant (Phalacrocorax brasilianus) by that species smaller size and small white chin patch, and from the similar-looking Anhinga (Anhinga anhinga) by that species’ longer neck and tail. Male and female Double-crested Cormorants are similar to one another in all seasons. The Double-crested Cormorant breeds in scattered locations along the Pacific coast of North America from Alaska to Baja California, along the Atlantic coast from Newfoundland to Florida, in the northern Great Plains, and in the West Indies. Southern breeding populations tend to be non-migratory, while northern breeding populations migrate south to the coasts, the interior southeastern U.S., and Mexico. Small numbers may breed or winter outside this species’ main range where habitat is appropriate. Double-crested Cormorants inhabit a variety of freshwater and saltwater wetland habitats, including rivers, lakes, marshes, and flooded grasslands. This species nests in trees surrounding bodies of water, on small islands, or on abandoned man-made structures near water. Double-crested Cormorants primarily eat small fish. On large bodies of water across the continent, Double-crested Cormorants may be seen floating low in the water, occasionally diving underwater for long periods while pursuing prey. Like many cormorants, this species may also be seen perched on rocks or snags with its wings outstretched and feathers ruffled. This species lacks the oily feather coating used by other water birds to keep dry and maintain buoyancy, and it has been suggested that this behavior allows the birds to dry their wings. Double-crested Cormorants are primarily active during the day.

Threat Status: Least Concern

  • Double-crested Cormorant (Phalacrocorax auritus). The Internet Bird Collection. Lynx Edicions, n.d. Web. 20 July 2012. .
  • Hatch, Jeremy J. and D. V. Weseloh. 1999. Double-crested Cormorant (Phalacrocorax auritus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/441
  • Peterson, Roger Tory. Birds of Eastern and Central North America. Boston: Houghton Mifflin, 1980. Print.
  • Phalacrocorax auritus. Xeno-canto. Xeno-canto Foundation, n.d. Web. 20 July 2012. .
  • eBird Range Map - Double-crested Cormorant. eBird. Cornell Lab of Ornithology, N.d. Web. 20 July 2012. .
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Distribution

Range Description

The Double-crested Cormorant is widely distributed across North America, from the Aleutian Islands and Alaska (USA) down to north-west Mexico on the Pacific coast, and from North Carolina (USA) down to Cuba on the Atlantic coast. Summer breeding grounds also include much of the United States and southern-central and eastern Canada1.
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Caribbean; North America
  • North-West Atlantic Ocean species (NWARMS)
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Caribbean; North America
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Double-crested cormorants breed across North America, as far north as southern Alaska. They winter in North America as far south as Sinaloa, Mexico, and are common on marine and inland waters throughout their range.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Hatch, J., D. Weseloh. 1999. Double-crested cormorant (Phalacrocorax auritus). Pp. 1-36 in A Poole, F Gill, eds. The Birds of North America, Vol. 441. Philadelphia, PA: The Birds of North America, Inc.
  • Pearson, T. 1936. Birds of America. New York: Garden City Books.
  • Perrins, C. 1990. The Illustrated Encyclopedia of Birds. New York: Prentice Hall Press.
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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southeastern Bering Sea and southern Alaska; southern British Columbia eastward through Manitoba to coastal Quebec and Newfoundland, south (in isolated colonies) to Baja California, coastal Sonora, central Chihuahua, central Durango, south-central Arizona, southern New Mexico, southern Texas, Gulf Coast, Florida, northern Bahamas, Cuba, Yucatan Peninsula, and Belize (Johnsgard 1993, AOU 1998). Breeding range in North America has expanded in recent years (Johnsgard 1993). Extirpated from Amchitka Island, Alaska, perhaps due to predation by arctic fox (ALOPEX LAGOPUS; Siegel-Causey et al. 1991). Occurs throughout most of the coastal breeding range and beyond when not breeding. NON-BREEDING: Pacific coast from Aleutians and southern Alaska south to Baja California and Nayarit; inland from Washington and Montana south to California and northeastern Colorado, southern Minnesota, and the Great Lakes south to northwestern Mexico, Oklahoma, Texas, and the Gulf states; and along the Atlantic coast, from Lake Ontario and New England south to Florida, Bermuda, the Bahamas, Greater Antilles, Yucatan Peninsula, and northern Belize (AOU 1998).

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Geographic Range

Double-crested cormorants breed across North America, as far north as southern Alaska. They winter in North America as far south as Sinaloa, Mexico, and are common on marine and inland waters throughout their range.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Hatch, J., D. Weseloh. 1999. Double-crested cormorant (Phalacrocorax_auritus). Pp. 1-36 in A Poole, F Gill, eds. The Birds of North America, Vol. 441. Philadelphia, PA: The Birds of North America, Inc.
  • Pearson, T. 1936. Birds of America. New York: Garden City Books.
  • Perrins, C. 1990. The Illustrated Encyclopedia of Birds. New York: Prentice Hall Press.
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Coastal and interior North America.
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Physical Description

Morphology

Cormorants are large birds (70 to 90 cm in length, 1.2 to 2.5 kg) with dark brown or black plumage that has a dull greenish or bronze sheen. They have lean bodies, long necks and relatively short wings. They have long beaks with a hooked upper mandible and bright orange-yellow skin that covers the face, throat and base of the bill. Their black feet are webbed feet and found on short legs, and their tails are wedge-shaped. During the breeding season, double-crested cormorants have two curly black crests on their heads, blue eyelids, a dusky bill and orange on the throat sac and lores. In the winter, adults lack the crests, show no blue on eyelids, have a yellow bill with red on gular sac, and yellow behind the ocher.

Males are slightly bigger than females. Juveniles are much duller in color than adults. They are usually dark brown with grayish or whitish coloring underneath. (Pearson 1936)

There are five subspecies of double-crested cormorants. These subspecies are differentiated by size and the color and shape of their crests.

Range mass: 1200 to 2500 g.

Range length: 70 to 90 cm.

Sexual Dimorphism: male larger; ornamentation

Other Physical Features: endothermic ; bilateral symmetry

Average basal metabolic rate: 5.6096 W.

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Physical Description

Cormorants are large birds (70 to 90 cm in length, 1.2 to 2.5 kg) with dark brown or black plumage that has a dull greenish or bronze sheen. They have lean bodies with long necks and short wings. They have long, hooked beaks and bright orange-yellow skin that covers their face and throat. They have black webbed feet and short legs. Their tails are wedge-shaped. During the breeding season, double-crested cormorants have two curly black crests on their heads, blue eyelids, a dusky-colored bill and orange on their throat. In the winter, adults do not have the crests or blue on their eyelids, and they have a yellow bill.

Male double-crested cormorants are slightly bigger than females. Juveniles are much duller in color than adults. They are usually dark brown with grayish or whitish coloring on their chest and belly.

There are five subspecies of double-crested cormorants. These subspecies are different in size and the color and shape of their crests.

Range mass: 1200 to 2500 g.

Range length: 70 to 90 cm.

Sexual Dimorphism: male larger; ornamentation

Average basal metabolic rate: 5.6096 W.

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Size

Length: 81 cm

Weight: 1818 grams

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Length: 74-91 cm, Wingspan: 122-137 cm
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species habitat ranges widely, including sheltered marine waters such as estuaries, bays and mangrove swamps, rocky coasts and coastal islands, and inland on lakes, rivers, swamps, reservoirs and ponds. Its diet it almost exclusively fish with a few crustaceans, with the prey species changing depending on locality. Prey is caught by pursuit-diving, and individuals can fish co-operatively, sometimes with thousands of birds together at one time. It begins laying from April to July, nesting on a wide variety of substrates forming colonies sometimes over thousands of pairs strong (del Hoyo et al. 1992).

Systems
  • Terrestrial
  • Freshwater
  • Marine
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Depth range based on 8322 specimens in 1 taxon.
Water temperature and chemistry ranges based on 109 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 4.935 - 24.843
  Nitrate (umol/L): 0.335 - 4.490
  Salinity (PPS): 30.118 - 35.736
  Oxygen (ml/l): 4.772 - 7.569
  Phosphate (umol/l): 0.081 - 0.788
  Silicate (umol/l): 1.016 - 16.169

Graphical representation

Temperature range (°C): 4.935 - 24.843

Nitrate (umol/L): 0.335 - 4.490

Salinity (PPS): 30.118 - 35.736

Oxygen (ml/l): 4.772 - 7.569

Phosphate (umol/l): 0.081 - 0.788

Silicate (umol/l): 1.016 - 16.169
 
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Double-crested cormorants are found in a variety of marine and inland aquatic habitats. They require water for feeding and nearby perches, such as rocks, sandbars, pilings, shipwrecks, wires, trees or docks for resting on and drying out during the day.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

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Comments: Lakes, ponds, rivers, lagoons, swamps, coastal bays, marine islands, and seacoasts; usually within sight of land. Nests on the ground or in trees in freshwater situations, and on coastal cliffs (usually high sloping areas with good visibility). See Spendelow and Patton (1988) for further details on nesting sites in different geographic areas.

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Double-crested cormorants are found in a variety of marine and inland aquatic habitats. They require water for feeding and nearby perches, such as rocks, sandbars, pilings, shipwrecks, wires, trees or docks for resting on and drying out during the day.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

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Depth range based on 8322 specimens in 1 taxon.
Water temperature and chemistry ranges based on 109 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 4.935 - 24.843
  Nitrate (umol/L): 0.335 - 4.490
  Salinity (PPS): 30.118 - 35.736
  Oxygen (ml/l): 4.772 - 7.569
  Phosphate (umol/l): 0.081 - 0.788
  Silicate (umol/l): 1.016 - 16.169

Graphical representation

Temperature range (°C): 4.935 - 24.843

Nitrate (umol/L): 0.335 - 4.490

Salinity (PPS): 30.118 - 35.736

Oxygen (ml/l): 4.772 - 7.569

Phosphate (umol/l): 0.081 - 0.788

Silicate (umol/l): 1.016 - 16.169
 
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Coastlines, bays, lakes and rivers.
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Northern coastal and especially interior populations migrate southward for nonbreeding season; migratory tendency is stronger on east coast than on west coast. Usually follows river valleys, coastlines, and water courses. Migrates day or night (Palmer 1962). East of the Rockies, migrates southward from northern latitudes in October-November, northward in April-May; breeders from the central and eastern parts of Canada and the northern U.S. winter mainly in the southern U.S. between Texas and Florida, with considerable overlap of different breeding populations on the wintering grounds; there is little intermixing of birds from east and west of the Rockies (Dolbeer 1991).

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Travel in flocks, mostly along rivers or coastlines.
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Trophic Strategy

Double-crested cormorants feed primarily on fish, but also eat insects, crustaceans and amphibians. They generally feed in shallow water (less than 8 m deep) within 5 km of shore, diving underwater to catch their prey. They may swallow small fish while underwater, but bring larger prey up to the surface to shake, clean or hammer on the water before consuming them.

When feeding on schooling fish, cormorants may feed together in flocks. They have a hook-like tip on the upper maxilla of their bill and specialized muscles that aid them in grasping their slippery prey.

Animal Foods: amphibians; fish; insects; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

  • Brooke, M., T. Birkhead. 1991. The Cambridge Encyclopedia of Ornithology. Cambridge: Cambridge University Press.
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Comments: Feeds opportunistically on fishes (usually less than 13 cm long); dives from surface of water; usually feeds in water < 15 m deep. Accused of reducing sport fish populations in New York, but this contention has not been documented (Carroll 1988). Eats mostly schooling fishes (in marine waters, mainly slow-moving species of bottom and mid-water), sometimes aquatic invertebrates and rarely small vertebrates other than fishes. Sometimes forages in compact flocks.

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Food Habits

Double-crested cormorants feed primarily on fish, but also eat insects, crustaceans and amphibians. They usually feed in shallow water (less than 8 m deep) within 5 km of shore. They catch prey by diving underwater to chase it. They may swallow small fish while underwater, but they bring larger prey up to the surface to shake it, clean it or hammer it on the water before eating.

When hunting schooling fish, cormorants may feed together in large flocks. They have a hook-like tip on their bill and specialized muscles that allow them to grasp their slippery prey.

Double-crested cormorants drink by dipping their bill into water, and then raising their head to let the water fall into their throat.

Animal Foods: amphibians; fish; insects; aquatic crustaceans

  • Brooke, M., T. Birkhead. 1991. The Cambridge Encyclopedia of Ornithology. Cambridge: Cambridge University Press.
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Fish mostly, but also crabs, shrimp, crayfish, frogs, salamanders, eels, snakes, mollusks, and plant material.
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Associations

Double-crested cormorants may nest with up to thirteen other species of colony-nesting birds. Within these mixed colonies, they may affect nest-site availability to other species, and provide food for the other species by means of chicks, eggs, pellets, regurgitated fish and stolen food. Cormorants also hunt in mixed flocks, benefiting others and benefiting others through their combined effort to find prey.

Double-crested cormorants impact the populations of the fish they consume.

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Gulls, crows and jays and grackles are probably significant predators of cormorant eggs and chicks. Coyotes, foxes and raccoons may also prey on cormorant chicks. Adult cormorants and chicks are susceptible to predation by bald eagles, and occasionally by great horned owls, caiman and brown pelicans.

When threatened by a predator, gulls may threaten the predator or vomit fish at them. If the predator is large, the adults usually leave the nest, and circle overhead.

Known Predators:

  • crows and jays (Corvidae)
  • grackles (Quiscalus)
  • coyotes (Canis latrans)
  • foxes (Canidae)
  • raccoons (Procyon lotor)
  • bald eagles (Haliaeetus leucocephalus)
  • great horned owls (Bubo virginianus)
  • caimans (Caiman crocodilus)
  • brown pelicans (Pelecanus occidentalis)
  • gulls (Larus)

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Ecosystem Roles

Double-crested cormorants nest in colonies with up to thirteen other species of birds. Within these mixed colonies, they may take nest sites away from other species. Other species, such as gulls may also benefit from the cormorants by eating their eggs and chicks, the pellets that they cast, and fish that they regurgitate. Other species may also steal food from the cormorants. Cormorants also hunt in flocks with other species. This may help the cormorants and the other species to find food more quickly.

Double-crested cormorants also affect the populations of the fish they consume.

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Predation

Larus, Corvidae and Quiscalus are probably significant predators of cormorant eggs and chicks. Canis latrans, foxes and Procyon lotor may also prey on cormorant chicks. Adult cormorants and chicks are susceptible to predation by Haliaeetus leucocephalus, and occasionally by Bubo virginianus, Caiman crocodylus and Pelecanus occidentalis.

When threatened by a predator, gulls may threaten the predator or vomit fish at them. If the predator is large, the adults usually leave the nest, and circle overhead.

Known Predators:

  • crows and jays (Corvidae)
  • grackles (Quiscalus)
  • coyotes (Canis_latrans)
  • foxes (Canidae)
  • raccoons (Procyon_lotor)
  • bald eagles (Haliaeetus_leucocephalus)
  • great horned owls (Bubo_virginianus)
  • caimans (Caiman_crocodylus)
  • brown pelicans (Pelecanus_occidentalis)
  • gulls (Larus)

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: In 1994, 852 colonies throughout North America (Tyson et al. 1997); number of defined occurrences may be somewhat lower.

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Global Abundance

100,000 to >1,000,000 individuals

Comments: Widespread and increasing. In 1994, estimated at least 372,000 nesting pairs throughout North America (Tyson et al. 1997). Relative abundance recorded on North American Breeding Bird Survey (BBS) survey-wide 1966-1996 was 0.76 birds per route. Highest relative abundance recorded in Minnesota (2.64 birds per route; Sauer et al. 1997). In winter, survey-wide Christmas Bird Count (CBC) shows 11.96 birds per 100 survey hours, 1959-1988. Highest CBC relative abundance recorded in North Carolina during the same period (170.64 birds per 100 survey hours; Sauer et al. 1996). High winter densities also occur in southern Florida, northern South Carolina, and along the lower Colorado River valley in the southwestern U.S. (Root 1988).

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General Ecology

Typically forages within about 20 km of roost site (Johnsgard 1993). No available information on interannual fidelity to colony; median distance of breeding birds to their natal site was < 25 kilometres (Dolbeer 1991). Increased sea surface temperatures, such as those associated with El Nino events, were correlated with decreases in nesting populations in Washington (Wilson 1991). Vigorously defends eggs and young against avian predators (Ehrlich et al. 1992), though large gulls, crows, and ravens are significant predators on eggs and young in some areas.

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Life History and Behavior

Behavior

Double-crested cormorants use calls and physical displays to communicate with one another. While cormorants use their small range of calls in certain social situations, they are largely silent. One example of the physical displays used to communicate between cormorants is the "wing wave display" used by males to attract a mate.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

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Communication and Perception

Double-crested cormorants use calls and physical displays to communicate with one another. While cormorants use their small range of calls to communicate some things, they are usually silent. One example of the physical displays that cormorants use is the "wing wave display" that males use to attract a mate.

Communication Channels: visual ; acoustic

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Life Expectancy

The oldest known wild double-crested cormorant lived to be 17 years and 9 months old. The average life expectancy for wild birds is 6.1 years.

Range lifespan

Status: wild:
17.75 (high) years.

Average lifespan

Status: wild:
6.1 years.

Average lifespan

Status: wild:
270 months.

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Lifespan/Longevity

The oldest known wild double-crested cormorant lived to be 17 years and 9 months old. The average life expectancy for wild birds is 6.1 years.

Range lifespan

Status: wild:
17.75 (high) years.

Average lifespan

Status: wild:
6.1 years.

Average lifespan

Status: wild:
270 months.

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Lifespan, longevity, and ageing

Maximum longevity: 19.5 years (wild) Observations: Maximum longevity from banding studies was 19.5 years (Blumstein and Moller 2008).
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Reproduction

Cormorants are monogamous and breed in colonies of up to three thousand pairs. The male chooses a nest site and then advertises for a female by standing in a “wing-waving display” that shows off the brightly-colored skin on his head and neck. Males also perform elaborate courtship dances, including dances in the water where they present the female with nest material. After forming a pair, double-crested cormorants lose their crests.

Double-crested cormorants do not defend a large territory around the nest. They defend a small area immediately around the nest that is less than one meter in diameter.

Mating System: monogamous

Double-crested cormorants breed between April and August, with peak activity occurring in May through July. The males arrive at the breeding colony first and chose a nest site. They then advertise for a mate. The male and female work together to repair an old nest or to build a new one of sticks, twigs, vegetation and flotsam and jetsam found nearby, including rope, fishnet, buoys and deflated balloons. The male brings most of the material to the female who builds the nest and guards it from other colony members who would otherwise steal the nest materials. The nests typically built on the ground, but are occasionally built in trees. After nest construction is complete, the female lays 1 to 7 (usually 4) pale bluish-white eggs with a chalky coating. The eggs are laid 1 to 3 days apart. Both parents incubate the eggs, which hatch asynchronously after 25 to 28 days. The newly hatched young are altricial, and are cared for by both parents. Both parents feed the chicks regurgitated food. The young begin to leave the nest when they are 3 to 4 weeks old. They can fly at about 6 weeks and dive at 6 to 7 weeks. The chicks become completely independent of their parents by 10 weeks of age. Double-crested cormorants do not breed until they are at least 2 years old.

Breeding interval: Double-crested cormorants breed once yearly.

Breeding season: Double-crested cormorants breed between April and August, with peak activity occurring in May through July.

Range eggs per season: 1 to 7.

Range time to hatching: 25 to 28 days.

Range fledging age: 3 to 4 weeks.

Average time to independence: 10 weeks.

Range age at sexual or reproductive maturity (female): 2 (low) years.

Range age at sexual or reproductive maturity (male): 2 (low) years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average eggs per season: 3.

Both parents incubate the eggs and care for the altricial chicks. The parents feed the chicks regurgitated food 2 to 6 times per day. On hot days, parents fetch water and pour it directly from their beak into the open mouths of the chicks.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

  • Hatch, J., D. Weseloh. 1999. Double-crested cormorant (Phalacrocorax auritus). Pp. 1-36 in A Poole, F Gill, eds. The Birds of North America, Vol. 441. Philadelphia, PA: The Birds of North America, Inc.
  • Landsborough, T. 1964. A New Dictionary of Birds. New York: McGraw-Hill Book Company.
  • Pearson, T. 1936. Birds of America. New York: Garden City Books.
  • Perrins, C. 1990. The Illustrated Encyclopedia of Birds. New York: Prentice Hall Press.
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Time of nesting varies geographically, with local variations, and among different years a particular colony. Nesting begins in winter in Florida, as late as early June in southern Alaska. Clutch size usually one to seven (average typically three or four). Incubation 24-33 days (average around 28-30), by both sexes in turn. Hatching success was 54-75% in three studies. Survival from hatching to fledging was 72-95% in two studies. First flight to water at about 35-42 days. Independent at about 9-10 weeks. Usually first breeds at three years, sometimes at two years, rarely at one year. Renesting following loss of clutch is fairly common. Nest in relatively dense colonies; nests only 0.6 - 2.0 meters apart (Hatch and Weseloh 1999). New colonies may be abandoned within a few years, but once well established, likely to persist (Hatch and Weseloh 1999). See Johnsgard (1993) for further information.

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Cormorants are monogamous and breed in colonies of up to three thousand pairs. The male chooses a nest site and then advertises for a female by standing in a “wing-waving display” that shows off the brightly-colored skin on his head and neck. Males also perform elaborate courtship dances, including dances in the water where they present the female with nest material. After forming a pair, double-crested cormorants lose their crests.

Double-crested cormorants do not defend a large territory around the nest. They defend a small area immediately around the nest that is less than one meter in diameter.

Mating System: monogamous

Double-crested cormorants breed between April and August. The males arrive at the breeding colony first and chose a nest site. Then they advertise for a mate. The male and female work together to repair an old nest or to build a new one. Nests are built of sticks, twigs, vegetation and whatever else the cormorants can find lying around. This can include rope, fishnet, buoys and deflated balloons. The male brings most of the material to the female who builds the nest. She also guards it from neighboring cormorants who try to steal the nest materials. Nests are usually built on the ground, but are sometimes built in trees.

After the nest is finished, the female lays 1 to 7 (usually 4) pale bluish-white eggs with a chalky coating. The eggs are laid 1 to 3 days apart. Both parents incubate the eggs, which hatch after 25 to 28 days. The newly hatched young are altricial, and are cared for by both parents. Both parents feed the chicks regurgitated food. The young begin to leave the nest when they are 3 to 4 weeks old. They can fly at about 6 weeks and dive at 6 to 7 weeks. The chicks become completely independent of their parents by 10 weeks of age. Double-crested cormorants do not breed until they are at least 2 years old.

Breeding interval: Double-crested cormorants breed once yearly.

Breeding season: Double-crested cormorants breed between April and August, with peak activity occurring in May through July.

Range eggs per season: 1 to 7.

Range time to hatching: 25 to 28 days.

Range fledging age: 3 to 4 weeks.

Average time to independence: 10 weeks.

Range age at sexual or reproductive maturity (female): 2 (low) years.

Range age at sexual or reproductive maturity (male): 2 (low) years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 3.

Both parents incubate the eggs and care for the altricial chicks. The parents feed the chicks regurgitated food 2 to 6 times per day. On hot days, parents fetch water and pour it directly from their beak into the open mouths of the chicks.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

  • Hatch, J., D. Weseloh. 1999. Double-crested cormorant (Phalacrocorax_auritus). Pp. 1-36 in A Poole, F Gill, eds. The Birds of North America, Vol. 441. Philadelphia, PA: The Birds of North America, Inc.
  • Landsborough, T. 1964. A New Dictionary of Birds. New York: McGraw-Hill Book Company.
  • Pearson, T. 1936. Birds of America. New York: Garden City Books.
  • Perrins, C. 1990. The Illustrated Encyclopedia of Birds. New York: Prentice Hall Press.
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First breeds at 3 years old. Nests built on cliff ledges in colonies. 3-4 eggs, incubated by both partners for 25-33 days. Young are fed by both parents. First flight occurs around 5-6 weeks old.
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Source: Gulf of Maine Area Census of Marine Life

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Phalacrocorax auritus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 4 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNATAGTCGGAACTGACCTCAGCCTGCTTATCCGCGCAGAACTCGGCCAACCAGGAACTCTCCTGGGAGATGACCAAATCTACAATGTAATTGTCACCGCCCATGCTTTCGTAATAATCTTCTTCATAGTAATGCCCATTATAATTGGAGGATTTGGAAACTGACTGGTCCCCCTCATAATCGGCGCCCCCGACATAGCATTCCCACGTATAAACAACATAAGCTTCTGACTCCTTCCACCATCATTCCTCCTCTTATTAGCCTCCTCTACAGNAGAAGCAGGCGCAGGTACAGGATGAACGGTATATCCACCCCTAGCCGGAAACCTAGCCCATGCCGGAGCCTCAGTCGACCTAGCCATCTTCTCCCTTCACTTAGCAGGAGTCTCCTCAATCCTAGGAGCAATCAACTTCATCACAACTGCCATTAACATAAAACCCCCAGCCCTGTCACAATACCAAACCCCACTGTTCGTTTGATCCGTACTAATCACCGCAATCTTACTCCTACTCTCACTTCCAGTCCTTGCTGCCGGAATCACCATACTCCTAACAGACCGAAACCTAAACACAACATTCTTTGACCCCGCTGGAGGAGGAGACCCAGTCCTATACCAACACCTATTCTGATTCTTCGGCCACCCAGAAGTCTACATCTTAATTCTC
-- end --

Download FASTA File

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Source: Barcode of Life Data Systems (BOLD)

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Statistics of barcoding coverage: Phalacrocorax auritus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 4
Specimens with Barcodes: 5
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

History
  • Least Concern (LC)
  • Least Concern (LC)
  • Least Concern (LC)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
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