McKay's Bunting breeds on islands in the Bering Sea and moves to the west coast of Alaska for winter.
Adults resemble Snow Buntings but are much whiter, with less black on the wings and tail. The sexes have similar plumage.
Of 83 nests studied on the east coast of St. Matthew Island in 1982, 1983, and 2003, 58 were in rock crevices on talus slopes. Other nests were in coastal cliffs, boulder fields, lake banks, vole tunnels, and under driftwood. Females built the nests; observations at seven nests showed construction taking four to five days.
During an observation lasting about five hours at one site on St. Matthew Island on 22 July 2024, adults collected insects, and one or more females fed juveniles.
An extinction-risk assessment has not been added yet.