Also known as the Grey Duck, the Pacific Black Duck hybridizes readily with introduced Mallards. In New Zealand such hybridization seriously threatens the native population, but in Australia the number of hybrids reported appears to be minimal. Two poorly differentiated subspecies are currently recognized by Clements et al (2019) but Carboneras & Kirwan (2019) and Marchant & Higgens (1990) treat the species as monotypic. The Australian population formerly assigned to subspecies A. s. rogersi is now merged with nominate. This common Australasian duck was formerly lumped with the Spot-billed Duck (Anas poecilorhyncha). Canon PowerShot SX60 HS.
References:
Carboneras, C. & Kirwan, G.M. (2019). Pacific Black Duck (Anas superciliosa). 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 https://www.hbw.com/node/52880 on 23 December 2019).
Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2019. The eBird/Clements Checklist of Birds of the World: v2019. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
Marchant, S.J.; Higgins, P. (eds) 1990. Handbook of Australian, New Zealand and Antarctic birds, Volume 1, Part B. Oxford University Press, Melbourne, Australia.
Williams, M.J. 2013. Grey duck. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz