This is an immature which lacks the adult's distinct white face. Formerly accidental this species recently colonized New Zealand with nesting first confirmed in 1941. The second nest was in 1946 and the third in 1952. Colonization continued rapidly in the 1960's and this species is now the most common heron in New Zealand. Adams (2013) recognizes the smaller race E. n. nana confined to New Caledonia and the Loyalty Islands; while Clements/eBird & HBW recognizes the darker E. n. parryi from NW Australia. However geographic variation is slight and HANZAB, IOC & H&M4 all consider the species to be monotypic. Species is sometimes placed in the genus Ardea. Canon PowerShot SX50 HS.
References:
Adams, R. 2013 [updated 2015]. White-faced heron. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Hancock, J. & J.Kushlan. 1984. The Herons Handbook. Harper & Row, New York.
Marchant, S. & Higgins, P.J. (editors) 1990. Handbook of Australian, New Zealand & Antarctic Birds. Volume 1, Ratites to Ducks. Melbourne, Oxford University Press.
Martínez-Vilalta, A., Motis, A., Kirwan, G.M. & Bonan, A. (2017). White-faced Heron (Egretta novaehollandiae). 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/52691 on 12 February 2017)