Phalacrocoracidae

Shags

The family of Phalacrocoracidae can be divided into two groups: the Cormorants and the Shags. The division into these two groups is based on ecological, behavioral and physiological characteristics (Johnsgard, 1993). 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 shags are divided in plates, very much like those of the tubenoses, without visible nostrils. See also anatomy  page.

This page deals with the seventeen species of the genus Leucocarbo. According to Johnsgard the former genera Leucocarbo, Notocarbo, Nesocarbo and Strictocarbo are lumped into the single genus Leucocarbo. The taxonomy of the shags is still subject of discussion in several species, such has the closely related forms of the Imperial and King Shag.

Shags are always coastal and vary not as much in size as the true cormorants. They are all more or less medium sized, compared with the true cormorants.

Genus Leucocarbo

• Socotra Shag Leucocarbo nigrogularis, Persian Gulf, south-eastern coast Arabian peninsula and adjacent islands.

• Cape Shag Leucocarbo capensis, endemic to coast south-western Africa.

Socotra Shag Leucocarbo nigrogularis Bahrein   Total: 132 mm; unsexed adult, occipital style missing

Cape Shag Leucocarbo capensis South Africa   Culmen: ca 54 mm; total: 116 mm, occipital style missing, unsexed adult.

• Guanay Shag Leucocarbo bougainvillii, Pacific coast of South America.

• Imperial Shag Leucocarbo atriceps, circumpolar in southern seas, eight subspecies of complex taxonomy. Many of them are sometimes considered full species.

•    Magellanic Blue-eyed Shag L. a. atriceps, Terra del Fuego.

•    Falkland Blue-eyed Shag L. a. albiventer, endemic to Falkland Is.

•    Antarctic Blue-eyed Shag L. a. bransfieldensis, Antarctic peninsula and Antarctic Archipelago.

•    Georgian Shag L. a. georgianus, South Georgia I.

•    L. a. melanogenis, endemic to Prince Edward, Marion and Crozet Is.

•   Kerguelen Shag L. a. verrucosis, endemic to Kerguelen Is.

•   Heard Shag L. a. nivalis, endemic to Heard I.

•    Maquarie Island Shag L. a. purpurascens, endemic to Maquarie I.

• Campbell Island Shag Leucocarbo campbelli, endemic to Campbell Is.

• King Shag Leucocarbo carunculatus, endemic to New Zealand, Marlborough Sound.

Stewart Island Shag  Leucocarbo (carunculatus) chalconotus Taiaroa Head, South Island, New Zealand   Culmen: 61.6 mm, total (ex. occ. style): 136. 9 mm, adult male.

• Stewart Island Shag Leucocarbo (carunculatus) chalconotus, endemic to New Zealand, Stewart I. and southern coast of South Island.

• Chatham Island Shag Leucocarbo (carunculatus) onslowi, endemic to Chatham Is.

• Auckland Island Shag Leucocarbo (carunculatus) colensoi,endemic to Auckland Is.

• Bounty Island Shag Leucocarbo (carunculatus) ranfurlyi, endemic to Bounty Is.

• Rock Shag Leucocarbo magellanicus, coast of South America from Santiago de Chile to Uruguay and Falkland Is.

• Pelagic Shag Leucocarbo pelagicus, from Baja California to Japan and Korea.

Pelagic Shag Leucocarbo pelagicus Location unknown   Culmen: ca 47 mm; total (ex. occ. style): 101,8;  unsexed adult

• Red-faced Shag, Leucocarbo urile, from Hokkaido, Japan to Alaska.

European Shag  Leucocarbo aristoteles ssp. aristoteles Tramore Ireland   Culmen: 57.0 mm, total (ex. occ. style): 119.6 mm, unsexed adult

• European Shag Leucocarbo aristoteles, three subspecies

•    L. a. aristoteles, northern European Atlantic coasts to Iberian Peninsula

•    L. a. desmarestii, Mediterranean coasts

•    L. a. riggenbachi, Atlantic coast of Morocco

• Red-Legged Shag Leucocarbo gaimardi, Pacific coast of South America and southernmost Argentina.

Spotted Shag  Leucocarbo punctatus Taiaroa Head, South Island, New Zealand   Culmen: 58.9 mm, total (ex. occ. style): 128.3 mm,  unsexed adult

• Spotted Shag Leucocarbo punctatus, New Zealand.

• Pitt Island Shag Leucocarbo (punctatus) featherstoni, endemic to the Chatham Is.

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Literature:

• Johnsgard, P.A., 1993, Cormorants, Darters, and Pelicans of the World, Smithsonian Institute, Washington/London.

 

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