Altho given specific rank the concensus of opinion seems to be that it is a subspecies — wherein I agree with the Ornithological Archbishop.
They are non-migratory and are found along the Lower California coast and adjacent shores of Mexico. They are more indolent than the eastern birds and Bancroft says they clear a place on the pebbly beach about ten inches in diameter, line the area neatly with pebbles and small pieces of shell, and deposit one, two or three eggs on this tile work.
Bancroft's notes indicate there are color phases, as one out of ten birds had dark underparts.
As above.