Family Cormorants (Phalacrocoracidae)

Critically Endangered

Chatham Shag (Phalacrocorax onslowi)


French: Cormoran des Chatham German: Chathamscharbe Spanish: Cormorán de las Chatham

Phalacrocorax onslowi

H. O. Forbes

, 1893,

Chatham Islands


Sometimes placed in Leucocarbo or Euleucocarbo. In past, often considered a race of P. carunculatus (which see). Monotypic.


Chatham Is (E of New Zealand), breeding on Chatham, Star Keys, Rabbit and Pitt, and on North East Reef.

Descriptive notes

63 cm; 1790–2525 g. Has crest on crown; head and upperparts including upperwing and outer sides of thighs black with blue to greenish-blue gloss, can have some hair-... read more


Male utters loud "urgh" in aggression; loud "borrr" or similar as sexual... read more


Marine. Forages near coast, no more than a few kilometres offshore, preferably in sheltered waters... read more

Food and feeding

Very little known. Probably mostly small fish. Presumably feeds mainly by pursuit-diving. Sometimes forms small feeding flocks.


Laying Sept–Dec, apparently with considerable variation even within a colony. Forms small monospecific colonies. Nest made from ice... read more


Sedentary; not recorded away from Chatham Is.

Status and conservation

CRITICALLY ENDANGERED. Very small total population within small range; numbers appear to be declining. Although colonies spread over several islands, extent of breeding range... read more

Recommended citation

Orta, J., Christie, D.A., Jutglar, F. & Kirwan, G.M. (2018). Chatham Shag (Phalacrocorax onslowi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 15 November 2018).