Breeds in Gulf of California (particularly Isla Rasa) south to Nayarit; also Baja California (from San Benito Is off Pacific coast) and northern very sparsely in southern California, occasionally and irregularly to San Francisco Bay.
 
Population
Estimated population is 530,000 (2010) and fluctuating.
Heermann's Gull (Larus heermanni) [XC382382]
by Paul Marvin from California, San Luis Obispo County, Monta\u00f1a de Oro State Park, United States (call)
Heermann's Gull (Larus heermanni) [XC362433]
by Paul Marvin from J Street Marina, Chula Vista, San Diego Co, California, United States (call)