The Glaucous-winged Gull is a year-round resident of the Pacific Coast from southern Alaska (including the coastal islands) south to northwestern Oregon (Sibley 2014). This species winters along the Pacific Coast from Oregon south through Baja California (Hayward and Verbeek 2008). In Montana, the Glaucous-winged Gull has several winter records over the past decade (Montana Bird Distribution Committee 2012).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.