- Order: Suliformes
- Family: Phalacrocoracidae
The Imperial Cormorant can be recognized by its blackish upperparts and white underparts, as well as blue eyering and yellow to orange caruncles in front of the eyes. Immatures have some glossy feathers on the back, the wings are brown, and they have a few streaks or spots of grayish brown on the breast.
The Imperial Cormorant belongs to the Blue-eyed Shag complex. This complex consists of 13 allopatric species that live on the coasts or islands of the Southern Ocean, and each one is defined by its geographical location (Orta 1992). The 13 species are very similar in their morphology. These species are: the Campbell Island Shag (Phalacrocorax campbelli), endemic to Campbell Island, south of New Zealand; the King Shag (Phalacrocorax carunculatus), endemic to New Zealand; the Steward Island Shag (Phalacrocorax chalconotus), limited to Stewart Island, New Zealand; the Chatham Island Shag (Phalacrocorax onslowi) endemic to Chatham Island, New Zealand; the Aukland Island Shag (Phalacrocorax colensoi) endemic to the Aukland Islands, New Zealand; the Bounty Island Shag (Phalacrocorax ranfurlyi) endemic to Bounty Islands, New Zealand; the Antarctic Blue-eyed Shag (Phalacrocorax bransfieldensis), which inhabits the Antarctic Peninsula; the South Georgian Blue-eyed Shag (Phalacrocorax georgianus) from South Georgia; the Kerguelen Shag (Phalacrocorax verrucosus) from Kerguelen Islands; the Macquarie Island Shag (Phalacrocorax purpurascens), from Macquarie Island; Crozet Shag Phalacrocorax melanogenis, endemic to Prince Edward, Marion and Crozet Islands; and Heard Shag Phalacrocorax nivalis, endemic to Heard Island. The species level relationships within the complex are still being resolved so some of the species presented above may be considered as subspecies by some authors.
Within its geographic distribution, the Imperial Cormorant breeds sympatrically with the Neotropic Cormorant (Phalacrocorax brasilianus), which is entirely blackish; the Red-legged Cormorant (Phalacrocorax gaimardi), which is mostly gray with a white patch on the neck, bright red tarsi and toes, and a bright yellow bill; the Guanay Cormorant (Phalacrocorax bougainvillii), which has a blacker neck and red skin around the eye; and the Magellan Cormorant (also known as the Rock Cormorant or Rock Shag; Phalacrocorax magellanicus), which has a black throat and breast, and bare red skin on the face.
Male and female have different vocalizations: males honk, and females hiss.
Detailed Description (appearance)
The following description is based on Johnsgard (1993).
Prebreeding adult: The crown, nape and hindneck are bluish black with a wispy recurved crest. The lower cheeks, chin and foreneck are white. The remiges and rectrices are black.
Postbreeding adult: Similar to the prebreeding but without the crest.
Inmature/subadult: Immatures are intermediate between the juvenal and definitive plumages. They have some glossy feathers on the back, their wings remained brown, the head is uncrested and they have a few streaks or spots of grayish brown on the breast. The black feathers of adults are represented by slaty feathers that fade to brownish.
Juvenile: They lack the crest and the caruncles. The feathers of the wings and lower back are edged with grayish white, and are relatively pointed. The crown and hindneck is black and the sides of the head and the lores are black grading into brownish black on the cheeks.
The following description is based on Johnsgard (1993).
Prebreeding adult: The iris is brown to pale green, and the bare eyering is bright blue. The nasal caruncles are saffron-yellow to gamboge-yellow. The bill is gray to olive or sooty. The inside surface of the bill is black, the mouth is red and the lores and gular skin is sooty with fine yellow specks. Tarsi and toes are pink to flesh-colored;the rear of tarsi and tips of toes are purplish gray.
Postbreeding adult: The caruncles are shrunken in size and duller in color, and the eyering and other softpart colors are generally less bright.
Inmature/subadult: The iris is brown, the eyering is dull lead blue and the facial skin and small caruncles are purplish brown. The tarsi and toes are dark gray with a pink tinge or pinkish edged with gray.
Juvenile: The iris is brown, and the eyering is purplish brown to black. The nasal caruncles are represented by brownish papillae and mingled with feathers. The bill is dark gray. Tarsi and toes are gray to brown.
The following measurements were taken from Svagelj and Quintana (2007)
Males (n = 93)
Wing length: mean 298 mm (range 287-317 mm)
Tarsus length: mean 69.4 mm (range 65.4-73 mm)
Bill length (exposed culmen): mean 58.7 mm (range 53.8-64 mm)
Bill depth: mean 12.5 mm (range 11-14.4 mm)
Head length: mean 139 mm (range 132-154 mm)
Mass: mean 2323 g (range 1920-2720 g)
Females (n = 95)
Wing length: mean 283 mm (range 269-298 mm)
Tarsus length: mean 65.7 mm (range 61.3-70 mm)
Bill length (exposed culmen): mean 55.3 mm (range 47.1-60.8 mm)
Bill depth: mean 11.1 mm (range 10-12.7 mm)
Head length: mean 132 mm (range 122-140)
Mass: mean 1972 g (range 1720-2300 g)
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In some individuals the demarcation line separating black and white of the head is located lower on the cheeks. White alar stripes are also sometimes present. Individuals with these characteristics are considered by some authors as a subspecies (Phalacrocorax atriceps albiventer) (Dorst and Mougin 1979) or as a separate species (Blake 1977).
The species limits of this group of birds remain controversial.
Gómez Laich, Agustina. 2012. Imperial Cormorant (Phalacrocorax atriceps), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=110076