[order] SULIFORMES | [family] Phalacrocoracidae | [latin] Phalacrocorax carbo | [UK] Great Cormorant | [FR] Grand Cormoran | [DE] Kormoran | [ES] Cormoran grande | [NL] Aalscholver
Subspecies
Monotypic species
Genus
The cosmopolitan genus Phalacrocorax of the Suliformes family includes thirty-five species frequenting coasts and islands. The face and throat are naked; the bill is long, and the upper mandible much curved at the point, while the lower supports a dilatable membrane which forms a gular pouch. The legs are short, strong, and abdominal, with three toes in front and one behind, all united; the claw of the middle toe is pectinated and probably used to dress the plumage and to free the bird from insect pests. The wings are of moderate length, and the tail-feathers stiff and rigid. Many of the species develop crests or wattles in the breeding season. These birds feed exclusively on fish. All Cormorants, Shags and Darters have a small bone at the back of the skull, the occipital style. This bone is flexibly attached to the skull and is supposed to have a function for the grasping ability of these birds. The ramphotecal coating of the bills of the cormorants are divided in plates, very much like those of the tubenoses, without visible nostrils.
Physical charateristics
The plumage of the Great Cormorant is black, though white
patches are present on the chin. The neck, which features a small crest of black feathers, is flecked with white or grey and the wings appear copper. The eyes of the Great Cormorant are green and its webbed feet are black. During breeding, white patches appear on the thighs of adult birds. The weight of the Great Cormorant is 2.5kg. The sexes appear similar, although the female bird is slightly smaller than the male. The plumage of the immature bird is brown.
The Great Cormorant is usually silent, although during courtship displays the male makes a ?kwer kwer’ sound while the female responds with soft purrs
patches are present on the chin. The neck, which features a small crest of black feathers, is flecked with white or grey and the wings appear copper. The eyes of the Great Cormorant are green and its webbed feet are black. During breeding, white patches appear on the thighs of adult birds. The weight of the Great Cormorant is 2.5kg. The sexes appear similar, although the female bird is slightly smaller than the male. The plumage of the immature bird is brown.
The Great Cormorant is usually silent, although during courtship displays the male makes a ?kwer kwer’ sound while the female responds with soft purrs
| wingspan min.: | 121 | cm | wingspan max.: | 149 | cm |
| size min.: | 77 | cm | size max.: | 94 | cm |
| incubation min.: | 28 | days | incubation max.: | 31 | days |
| fledging min.: | 45 | days | fledging max.: | 31 | days |
| broods: | 1 | eggs min.: | 3 | ||
| eggs max.: | 5 |
Range
Eurasia, Australasiastralia, Oriental Region : also Northeast NA, North AF
Habitat
In spite of its preference for extensive areas of permanent freshwater, the Great Cormorant is not confined to these and is often observed on coastal inlets and estuaries.
Reproduction
The Great Cormorant establishes breeding colonies that may include 2 000 breeding pairs, although smaller colonies are typical. These colonies are often shared with other species of waterbirds including grebes and other species of Cormorants. Breeding occurs throughout the year, although it is more common in Autumn and Spring. During courtship the male attracts a mate when he is resting on the water. The male raises and lowers his wings while he holds his head and tail upright, exposing the white plumes on his rump. When the wings are raised. the male vibrates them rapidly. Another form of display is when the male swings his head back and forth, holding his tail erect and calling loudly. The female responds by swinging her head slightly and ?purring’.
Both adults build their nest in a tree or on the ground. Because it is used by different breeding pairs for many years, the nest, which is made from dry sticks and twigs, may be more than 100cm deep. The female lays one egg every 2-3 days until she has a clutch of 3-4 eggs. The eggs are oval, blue-white and measure 66mm in length and 41mm in
width. Both adults assist the egg’s incubation. They place their webbed feet under the eggs and rest their warm bodies over them. The eggs hatch in 28-31 days.
Hatchlings are dependent on their parents for up to 70 days. The hungry chicks peck the adults’ throats, causing them to regurgitate food. The young birds beg for water by holding their open bills upward in a silent gesture. The parents respond by collecting water in their bills and pouring it into the chicks’ mouths. Hatchlings often fall prey to raptors such as the Whistling Kite before they fledge at 50 days.
Both adults build their nest in a tree or on the ground. Because it is used by different breeding pairs for many years, the nest, which is made from dry sticks and twigs, may be more than 100cm deep. The female lays one egg every 2-3 days until she has a clutch of 3-4 eggs. The eggs are oval, blue-white and measure 66mm in length and 41mm in
width. Both adults assist the egg’s incubation. They place their webbed feet under the eggs and rest their warm bodies over them. The eggs hatch in 28-31 days.
Hatchlings are dependent on their parents for up to 70 days. The hungry chicks peck the adults’ throats, causing them to regurgitate food. The young birds beg for water by holding their open bills upward in a silent gesture. The parents respond by collecting water in their bills and pouring it into the chicks’ mouths. Hatchlings often fall prey to raptors such as the Whistling Kite before they fledge at 50 days.
Feeding habits
The Great Cormorant feeds on fish, crabs, frogs and various insect species. Food is gathered underwater, but the Great Cormorant seldom dives to depths of more than 100cm. A typical dive lasts for less than 60 seconds. The Great Cormorant uses its webbed feet and its wings to propel itself underwater.
Conservation
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.
This cormorant has a wide distribution along the Atlantic coasts of Europe, from the Balkan Peninsula to India and China, in Africa, Australia and north-eastern North America. The continental race sinensis inhabits the lowlands along the North Sea and the Baltic Sea, central and Eastern Europe. This population had been reduced to 3000-5000 individuals during the first half of the twentieth century, but after the 1970’s it increased rapidly. The total population of the European Union is now estimated at 55000 breeding pairs and the total European population at 160.000 breeding pairs. The comeback of this species seems to be linked to the increase of fish stocks following large-scale eutrophication of water bodies and to the increase of fishponds.The species continued to increase during 1990-2000, with almost all national trends either stable
or increasing, including those of key populations in Denmark, Ukraine and Russia.
This cormorant has a wide distribution along the Atlantic coasts of Europe, from the Balkan Peninsula to India and China, in Africa, Australia and north-eastern North America. The continental race sinensis inhabits the lowlands along the North Sea and the Baltic Sea, central and Eastern Europe. This population had been reduced to 3000-5000 individuals during the first half of the twentieth century, but after the 1970’s it increased rapidly. The total population of the European Union is now estimated at 55000 breeding pairs and the total European population at 160.000 breeding pairs. The comeback of this species seems to be linked to the increase of fish stocks following large-scale eutrophication of water bodies and to the increase of fishponds.The species continued to increase during 1990-2000, with almost all national trends either stable
or increasing, including those of key populations in Denmark, Ukraine and Russia.
Migration
Migrant or partial migrant in most northerly populations, but sedentary or dispersive throughout most of range; migrants frequently winter within breeding range of species. Race sinensis fairly migratory, but variable with region and year: W populations move S towards Mediterranean, wintering inland and on coast, and reaching Persian Gulf. Nominate carbo widely dispersive, wintering mainly on coasts around breeding areas, though many inland in Ireland; populations of N North America and Greenland regularly move S, reaching New Jersey and sometimes Florida. In Australia, movements essentially nomadic and dispersive, related to cycles of flooding and drought.
Distribution map
