Scientific Name: Larus Heermanni
Population Estimate: 530K
Range / Habitat: Heermann’s gull breeds off the coast of Mexico and in the Gulf of California, particularly on Isla Rasa, where the population has a stronghold. Very occasionally it is seen breeding in San Francisco Bay. Non-breeders spend the breeding season at the wintering sites along the coasts of California and British Colombia.
Field Notes: The Heermann's Gull (Larus heermanni) is distinctive with a dark grey-brown back and wings, pale grey underside and rump, and white head, tips to the tail and wing feathers. The bill is bright red and sometimes tipped with black. The legs are black. Non-breeding adults have grey or brown streaks on the head and immature birds are dark brown all over, with a pale base to the red bill.