The Hermann's Gull or Heermann’s Gull is the only American gull with a grey body and white head.
All in a Name
The Hermann’s Gull or Heermann’s Gull is called Gaviota de Heermann or Gaviota Mexicana in Spanish. Its scientific name is Larus heermanni. The species is named after Adolphus Heermann, a naturalist, in 1852.
Heerman’s Gull is a member of the Larus genus and Laridae family.
The Hermann's Gull is a medium-size gull, similar in size to the ring-billed gull but stockier. The Hermann's Gull is eighteen to twenty one inches long, with a three and a half to four foot wing span. The Hermann's Gull weigh one to two pounds.
The adult has a gray body with a darker back, but its head is white. The bill is red with a black tip in adults. The juveniles have a grayish-brown body all over with buff edges on the feather tips. Young Herman gulls look like jaegers, but jaegers have white patches on their wings the Hermann’s Gull does not. Heerman’s Gulls not yet old enough to breed (less than two winters old) have pink or light beige bills that darken at maturity. Non-breeding adults have a dark streaked head. The body becomes more grayish over time. Their eyes are dark. Their feet are black.
The Hermann's Gull is a migratory gull. The Hermann's Gull spend the winter in California and summer in the Pacific Northwest and Canada. The Herman’s Gull is the only one with a breeding range south of the United States. The breeding season for these birds in is June and July, but breeders arrive in March and April to get a good nesting site. The Hermann's Gull prefer to nest on dry offshore islands and rarely come inland. The vast majority of the birds nest on only one island, Isla Raza. One major weather disaster like a hurricane could wipe out most of the species. For this reason, the species is considered “near threatened” by the IUCN. That island is a wildlife sanctuary. Of the five to ten percent of those that do not nest on Isla Raza, they are found throughout the Sea of Cortez; few nest as far south as Nayarit, Mexico.
The Hermann's Gull nest on the ground in large colonies. The nest is a shallow scrape in the soil lined with feathers and grass. The female lays one to three pale grey or olive green eggs with brown splotches. Both parents help incubate the eggs fro around four weeks and feed the young.
The Hermann's Gull eat small fish, marine invertebrates, trash, carrion, lizards, and insects. The Hermann's Gull eat less carrion than other gulls.
The Hermann's Gull birds regularly steal food from other birds, especially pelicans. The Hermann's Gull also steal food from marine mammals. The Hermann's Gull will plunge into the water to catch fish, hover over waves, and pick food from the surface.
The Hermann's Gull birds tend to associate with brown pelicans.
The Hermann's Gull birds live along the Pacific Coast. The Hermann's Gull prefer the shore and dry islands where there are fewer predators.
In the winter, the Hermann's Gull is found along the coast of California and Baja, Mexico. In the summer, the Hermann's Gull is found along the coast of Oregon, Washington, and British Columbia, Canada.
A few Heerman’s Gulls have tried establishing breeding sites on Alcatraz Island in California, but so far have been unsuccessful.