Imperial shag
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SPECIES
Leucocarbo atriceps

The imperial shag or imperial cormorant (Leucocarbo atriceps ) is a black and white cormorant native to southern South America, primarily in rocky coastal regions, but locally also at large inland lakes. Some taxonomic authorities, including the International Ornithologists' Union, place it in the genus Leucocarbo, others in the genus Phalacrocorax. It is also known as the blue-eyed shag, blue-eyed cormorant and by many other names, and is one of a larger group of cormorants called blue-eyed shags. The taxonomy is very complex, and several former subspecies are often considered separate species.

Appearance

The imperial shag has a total length of 70–79 cm (28–31 in) and weighs 1.8–3.5 kg (4.0–7.7 lb), with males usually larger than females. It is endowed with glossy black feathers covering most of its body, with a white belly and neck. It possesses a distinctive ring of blue skin around its eyes, an orange-yellow nasal knob, pinkish legs and feet, and an erectile black crest. During the non-breeding season, adults lack the crest, have a duller facial area, and less/no white to the back/wings. It has a serrated bill used for catching fish.

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The group varies primarily in the amount of white on the cheeks/ear-coverts, wing-coverts and back. Most taxa have white cheeks and ear-coverts, but these are black in albiventer, purpurascens and melanogenis. Chicks are uniform brownish, and immatures are brownish and white (instead of black and white), have dull facial skin, and lack the orange-yellow nasal knob and blue eye-ring.

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Imperial shag habitat map
Imperial shag
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Habits and Lifestyle

Seasonal behavior

Diet and Nutrition

The diet of this species consists of small benthic fish, crustaceans, polychaetes, gastropods and octopuses. They primarily feed on fish, especially Argentine anchoita,. Mean diving depth is almost 25 m (82 ft), and they have been filmed diving as deep as 60 m (200 ft) to forage on the sea floor. Most feeding takes place in inshore regions, but at least some populations will travel some distance from the shore to fish.

Mating Habits

This is a colonial, monogamous species. The colonies are usually relatively small, but some consist of hundreds of pairs and are often shared with other seabirds such as rock shags, southern rockhopper penguins and black-browed albatrosses. Up to five eggs (usually two or three) are placed in a nest made of seaweed and grass, and cemented together with mud and excrement. The eggs usually hatch in about five weeks, and are brooded by both parents. Many chicks and eggs are lost to predators such as skuas and sheathbills.

Population

Population number

Overall this species is not considered threatened and is consequently listed as Least Concern by BirdLife International and IUCN. Most subspecies are relatively common with estimates of over 10,000 pairs of each

References

1. Imperial shag Wikipedia article - https://en.wikipedia.org/wiki/Imperial_shag
2. Imperial shag on The IUCN Red List site - https://www.iucnredlist.org/species/22729686/133554713

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