Great Cormorants are sea birds. These birds are commonly known as the Black Shag in New Zealand and were formerly known as the Great Black Cormorant in the Northern Hemisphere.
About Great Cormorants
The taxonomical term for this bird is Phalacrocorax carbo. The genus name comes from two Greek words, Phalakros and Korax which mean Bald and Crow respectively. The species name, Carbo is Latin for Charcoal which justifies the fact that the adult male Great Cormorants are charcoal black in color.
Are wild birds being trained to catch fish? Now that is something interesting. So let’s find out more about these birds.
● Great Cormorant Photos, color pattern, song
● Great Cormorant Size, eating behavior, habitat
● Great Cormorant Range and migration, nesting
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Great Cormorant Color Pattern
As the species is named Carbo or Charcoal in Latin, the usual color of Great Cormorants is charcoal black. These birds also have a white throat and yellowish skin near the bill. The breeding adults develop a white patch on the thigh and white neck feathers. The juveniles however are dark brownish in color. They have a whitish throat and belly with some brownish streaks at the edges. Great Cormorants have overall dark legs and feet as well.
There is a very fascinating pigment anomaly of these birds that very rarely leads to a Great White Cormorant which is actually just an Albino version of the exact same bird.
Description and Identification
The adults of the species are black and the juveniles are brownish. They can be easily identified from these color differences. The white throat that is unique to the species is also a factor of identification while the patch on the thigh helps in identifying the breeding adults.
These birds can be spotted fishing by diving head-on into the water as they mostly feed on the bottom-living fishes. They can swim on the surface of the water as well.
These birds are usually seen out of the water the majority of the time, resting, digesting, and drying their wings. They fly strongly with deep wing-beats like Geese.
Similar species of Cormorants include Brandt’s Cormorant, Pelagic Cormorants, Neotropic Cormorants, and Double-crested Cormorants. But if observed carefully, Great Cormorants cannot be easily confused with the others as all of them have some unique feature of identification that the others lack. In appearance, Great Cormorants are the most similar to the Double-crested Cormorants however the latter has a red or orange skin near the bill that the Great Cormorant lacks.
Great Cormorant Song
Great Cormorants are not songbirds thus they do not have sing notes. Rather these birds have very few calls. These birds are usually noisy but the breeding pairs are particularly vocal. Great Cormorants make calls that sound like deep grunts. Their dispute calls sound like a low and deep “kek kek” grunting that has a slower pace whereas the colony calls are longer and faster.
Great Cormorant Size
Great Cormorants are somewhere between a crow and a goose. Relatively, these birds are larger than Double-crested Cormorants but smaller than Brown Pelicans. In fact, Great Cormorants are the largest of all Cormorants. These birds measure around 33.1-35.4 in (84-90 cm) in length and weigh 91.7-130.5 oz (2600-3700 g) with a wingspan of
51.2-63.0 in (130-160 cm).
Great Cormorant Behavior
Great Cormorants occur in flocks; however, their flocks aren’t as big in size as the flocks of Double-crested Cormorants. Most of the time through the day, these birds are spotted perched out of the water quietly resting, stretching, and preening. When they forage, they dive from the surface of the water and swim in the depths of it. Unlike ducks and
Geese, Great Cormorants lack waterproof plumage. Thus, they have to keep coming ashore and dry themselves as the plumage gets soaking wet. These birds dry their plumage by sunbathing and while doing so they hold their wings open for long periods of time.
Courting practices of Great Cormorants include males displaying from their territories. The male birds acquire very small territories, usually just the nest site. They open their wings and show their white breeding patch on the thigh as a courting display. Females, if interested, engage males in a series of courting displays including, gargling, pointing,
preflight, post-landing, hop, and kink-throat. These displays continue throughout the period of nesting and chick-rearing, as such displays help the pair to keep the binding tight. Great Cormorants are usually monogamous but there have been some extra-pair copulation practices commonly observed in the European populations.
During the time of nesting, when a different male approaches the nest, the male threatens it by leaning down while holding the tail up and opening the wings and wings. They also wag their head erratically and occasionally give out coarse threat calls. During child-rearing, both the members of the pair take care of the children and defend the nest. When approached by others, they go through something called “Nest Worrying”. This includes the birds clutching a piece of the vegetation in their bill and wagging it to shoo the invader away.
What do Great Cormorants Eat?
Great Cormorants are fish-eating carnivores. Their main diet includes bottom-dwelling fish. These birds forage by diving into deep waters and swim using their flipper-resembling duck-like feet and navigate with their tails.
Their prey includes fish like sculpins, rock gunnel, pollock, cunner, mummichog, Atlantic cod, winter flounder and other flatfishes, and tautog. Sometimes, they also eat small fishes that swim around in schools (a group of fish) such as Sandlance and Capeline and small crabs.
Great Cormorants swallow some of the smaller prey while submerged in water whereas they bring the larger fish to the surface to kill it and soften the meat before consuming. These birds are excellent foragers and studies have revealed that some of them only hunt for as little time as 20 minutes every day.
Great Cormorant Habitat
North American Great Cormorants live in the rocky shores of sea coasts throughout the year. But During the breeding seasons, they shift towards cliffs and rocky islands for nesting and even prefer stunted conifers sometimes. They try to stay away from human activities as much as possible as they prefer not to be disturbed during nesting and child-rearing. These birds also find places with no possible mammalian predators.
They usually perch on rocks when out of the water but can also be spotted on jetties, shipwrecks, ruins of manmade structures, buoys, channel markers, and pilings.
Their preferred habitats during migrations and winters are very identical and include the mid-Atlantic state rivers with sandy shores, sandbars, and edges of river ice. Often Single Great Cormorants have been found far inland living at lakes and reservoirs. In such sub context, they may perch on water control structures, dead trees, piers and
other structures commonly used by the Double-crested Cormorant.
Range and Migration
The range of Cormorants includes the rocky Atlantic Shoreline in the North American continent, Mid Atlantic states with rivers, Canadian maritime province, and the far islands with lakes.
Some subspecies of Great Cormorants also live in the lakes of Serbia and some are also found in Australian waters.
Most of the birds only breed in the Northern part of the Atlantic breeding range but during winters these birds usually migrate towards the south. During winters, Great Cormorants shift towards any place with good availability of fish.
Great Cormorant Lifecycle
Female Cormorants make the nest and lay around 1-7 eggs. These eggs are pale bluish-green with a chalky white covering them. The hatchlings are naked and helpless with black skin. The younger ones are fed fish by their parents. The adults vomit out the catch and it’s usually semi-digested and the chicks retrieve it from their mouths.
The average life span of the Great Cormorants is nearly 26 years. However, the mortality rates for juvenile birds are very high. Approximately a good 40% of juvenile birds do not survive after leaving their nests whereas the mortality rate decrease for the adult birds up to only 10-20%.
Usually, Great Cormorants make their nests on rocky islands and cliffs near the waterline to over 100ft over the water level. The male chooses the site with a flat surface for the nest to be built upon. Sometimes, they also make their nest on stunted trees, ship debris, or structures like building ruins. Great Cormorants are pretty adaptive when it comes to nesting and tend to easily use whatever is available.
Male birds also bring material to build the nest and give it to the female who then builds it. The nests are made by carefully assembling sticks and algae and measure on average above 19 inches across and 8.8 inches high.
Anatomy of a Great Cormorant
Great Cormorants are medium size birds with extraordinary capabilities of swimming, diving, and foraging underwater. Their main diet includes bottom-dwelling fishes and thus they dive into deep waters to hunt fish. So for diving and swimming underwater, these birds have developed bodily features to facilitate their voyaging.
Great Cormorants have feet that resemble flippers just like ducks, loons, geese, and swans. Such foot structures help these birds to paddle through water easily and swim well. Great Cormorants dive head-on into waters. When submerged, these birds swim downwards with the help of their feet and strong legs and navigate with their tails.
These birds mostly prefer diving in waters that are 30 feet deep whereas, they can also dive deeper; up to 100 feet to reach the bottom of the waters.
Great Cormorants also have a heavy hooked bill that is perfect for catching and extracting fish from under the submerged rocks at the bottom of the water levels. One drawback of these birds’ anatomy is that their plumage is not waterproof and as a result of diving into waters, they come up to the shores soaking wet. Great Cormorants are often spotted with open wings. They hold their wing up while perched on elevations and have their backs towards the sun and face the wind flow. This position probably helps them feel warm and dry their plumage faster.
Great Cormorants have been being used for fishing since the 5th century and thus they have a history of living very closely with human beings. In the 5th century, Fishermen in Japan and China put tethered rings around these birds’ necks and let them dive into the water to catch fish. Later, after being trained, the birds were able to do fishing for the
fishermen even without the tethered rings. In the 20th century, the Greeks and Macedonians used to keep Great Cormorants and train them to herd fish towards their nets.
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Bird Watching Binoculars for Identifying Great Cormorants
The most common types of bird watching binoculars for viewing Great Cormorants are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.
Great Cormorant Stickers
Stickers are a great way for you to display your love for bird watching and the Great Cormorant. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.
Bird Feeders For Great Cormorants
There are many types of bird feeders. Here are our favorite bird feeders for your backyard. We use all of these bird feeders currently. Kids will have a great time watching birds eat at these bird feeders. Using this collection of bird feeders will provide a wide variety and many types of birds.
Best Bird Houses For Great Cormorants
There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.