Distribution in the Americas
Nonbreeding visitor to the coasts of southern South American, in southern Chile (Jaramillo 2003), and the coasts of Argentina (Mazar Barnett and Pearman 2001) and Uruguay (Gore and Gepp 1978). Vagrant north along the coast to of Brazil (Sick 1993), even reaching northeastern Brazil (Shirihai 2008).
Distribution outside the Americas
Snowy Sheathbills breeds in coastal regions of the Antarctic Peninsula south to 65º S, and on South Georgia, South Orkney, and South Shetland islands. Occurs north to southern South America and to the Falklands Islands when not breeding. Ship-assisted birds have reached South Africa and even Europe (Shirihai 2008).
Sheathbills inhabit coastal regions from the Antarctic Peninsula north to the subantarctic islands and southern South America. Penguins, and to a much lesser extent, other colonial seabirds, notably cormorants and albatrosses, and seals play important roles in their lives. Both species of sheathbills almost always breed in parts of penguin colonies, and their breeding schedule is tied with that of the penguins. Oftentimes the nest is in a cavity that is surrounded by penguins. The sheathbills scout the penguin colonies for food. Cormorant colonies are used by breeding sheathbills in the same way, but albatrosses and petrels are exploited opportunistically. Additionally, the Snowy Sheathbill may be found among pack ice during the pupping season of the Weddell Seal (Leptonychotes weddelli).
Away from seabird colonies, sheathbills forage among rotting piles of kelp wrack along the shorelines on sandy and rocky beaches. Sheathbills will also forage for invertebrates on the lowland bogs, meadows, and tussock grass on some islands, and they can sometimes wander more than 1 km from the shore. At Antarctic and subantarctic research stations, these birds feed off of kitchen scraps and other refuse (Forster 1996).
In the past, the Snowy Sheathbill was attracted to shore-based whaling or sealing operations in the Antarctic region for resources (Shirihai 2002).