In North America, the Mew Gull breeds in Alaska, northwestern Canada, and the coast of British Columbia and winters along the Pacific coast from Alaska to Baja California. The species is an uncommon migrant to Montana with fewer than five observations reported in the typical year (Moskoff et al. 2002, MTNHP 2019).
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.
Mew Gulls migrate along the west coast to California.