This is a strictly coastal species. Unlike most true geese, these "sheldgeese" (genus Chloephaga) usually show considerable sexual dimorphism. Here the male is pure white, while the female is very dark with white restricted to the inner wing and lower belly. The adult female (top) has green iridescence on its greater coverts lacking in juveniles. Unlike other sheldgeese, we never encountered these birds in flocks. Instead they were usually in pairs. Two subspecies are recognized. This is the larger C. h. malvinarum which is resident on the Falklands. The nominate race on mainland South America is smaller with a noticeably smaller bill.
Canon PowerShot SX50 HS.
References:
Carboneras, C. & Kirwan, G.M. (2018). Kelp Goose (Chloephaga hybrida). 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/52830 on 13 May 2018).