These are not really geese, but "sheldgeese" more closely related to shelducks than to true geese. Males have white heades, females have brown. Two subspecies are recognized. This is the larger race C. p. leucoptera where the males are always white breasted, not barred. It is confined to the Falkland Islands and may be a cryptic species. Mainland males are polymorphic, some having barred breasts and others have white breasts. A common species, numbers continue to be stable or increase despite persecution by sheep ranchers. Formerly called Magellan Goose. Canon PowerShot SX50 HS
References:
Carboneras, C. & Kirwan, G.M. (2018). Upland Goose (Chloephaga picta). 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/52829 on 5 May 2018).
Madge, S. & Burn, H. (1988) Waterfowl. An identification guide to the ducks, geese and swans of the world. Houghton Mufflin, Boston.
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.
Todd, F. (1979). Waterfowl. Ducks, Geese & Swans of the World. Sea World, San Diego.