Larus heermanni
The Heermann's Gull (Larus heermanni) is a striking medium-sized gull, distinguished by its unique dark-bodied, pale-headed appearance, particularly in breeding plumage. Adults measure about 48-56 cm (19-22 inches) in length with a wingspan of 124-132 cm (49-52 inches) and weigh between 350-600 grams. Breeding adults sport a sooty-gray body, blackish primaries, and a contrasting pure white head, punctuated by a vibrant red bill with a black tip. Non-breeding adults develop a streaky gray head...
Primarily a coastal and marine species, inhabiting sandy beaches, rocky shores, and offshore islands for breeding and roosting. It remains at sea level, rarely venturing far inland.
The primary diet consists of small schooling fish, predominantly Pacific Sardines (Sardinops sagax) and Northern Anchovies (Engraulis mordax), obtained through surface-dipping, plunge-diving, and highly specialized kleptoparasitism. They also consume crustaceans and occasionally scavenge.
Heermann's Gulls are highly social and diurnal, often observed in large flocks, especially during the non-breeding season and when roosting on sandy beaches or offshore waters. Their foraging strategy is characterized by opportunistic surface-dipping and plunge-diving for small schooling fish, bu...
The Heermann's Gull exhibits a unique and reverse-migration pattern among North American gulls. Its primary breeding grounds are almost exclusively concentrated on islands in the Gulf of California, Mexico, with over 90% of the global population nesting on Isla Rasa. Post-breeding, these gulls un...
Least Concern
- The Heermann's Gull is the only gull species that breeds almost exclusively south of the United States border (primarily Baja California) and then migrates north along the Pacific Coast of North America to feed during its non-breeding season. - It is a master of kleptoparasitism, famously steal...