Very similar to the Auckland Islands Shag (Phalacrocorax colensoi), the Campbell Islands Shag is distinguished by its solid black foreneck sharply demarcated from its white chest in a straight line as seen here. Some Auckland Island Shags look similar but the white chest invades the black foreneck in an inverted "U" shape. These are the only shags on Campbell Island. They nest November to February on cliff ledges. This species is listed as "vulnerable" by IUCN because of its extremely limited breeding range. Its world population is estimated to be about 8000. This species is lumped with the Auckland and Bounty Islands Shags by H&M4 following a more traditional biological species approach. Canon PowerShot SX50 HS.
References:
Orta, J., Christie, D.A., Jutglar, F. & Kirwan, G.M. (2017). Campbell Shag (Phalacrocorax campbelli). 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 http://www.hbw.com/node/52647 on 7 March 2017).
Marchant, S. & Higgins, P.J. (coordinating editors) 1990. Handbook of Australian, New Zealand & Antarctic Birds. Volume 1, Ratites to ducks. Melbourne, Oxford University Press.
Shirihai, H. (2002) A Complete Guide to Antarctic Wildlife. The Birds and Marine Mammals of the Antarctic Continent and the Southern Ocean. Princeton University Press: Princeton & Oxford.
Szabo, M.J. 2013. Campbell Island shag. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz