Heermann's Gull is a beautiful and unique gull of the Pacific Coast.
They have an extremely limited breeding range, with 90% of the world's
population of the species breeding on a single island in Mexico, Isla Rasa.
However, they disperse widely after the breeding season, with birds
regularly moving north along the Pacific Coast as far as British Columbia.
Their movements northward appear to be timed to the movements of
Brown Pelicans. Heermann's Gulls
will often follow Brown Pelicans, attempting to steal fish that Pelicans (or
other birds) have caught.
Habitat: Mostly found near the Pacific Coast,
close to the shoreline. There, it will use a variety of habitats
outside of the breeding season, depending on food availability. They
are extremely rare away from the coast, typically not even venturing a few
miles from the ocean. They can sometimes be found far out to sea,
Diet: Feeds heavily on small fish, as well as
other marine life such as small crustaceans, mollusks, insects, and marine
worms. Will also occasionally steal eggs from nests, and will feed on
Behavior: When searching for fish, they fly close
to the ground, dipping down to the water's surface or plunging into the
water when a fish is spotted. Stealing fish and other food from other birds
is another favored foraging technique. They will occasionally feed on
human refuse, but not as much as many other gull species.
Nesting: The nest of a Heermann's Gull is often
just a simple scrape on the ground with a minimal lining of grasses and
feathers. Both the parents help to incubate the eggs. Both parents
feed the young upon hatching.
Song: Has a nasal koww call, but is
usually silent when away from their breeding grounds. On the breeding
grounds, has a low-pitched, nasal trumpeting call.
Migration: Heermann's Gulls consistently move
northward along the Pacific coast after the breeding season. While
nearly all breeding occurs on Isla Rasa island in Mexico, post-breeding
dispersal brings birds as far north as British Columbia in the summer
Distinctive gray plumage and red bill make the Heermann's Gull distinctive
and unlikely to be confused with other gull species, if seen well.
Conservation Status: Nearly 90% of the world's
population of Heermann's Gulls nest on one island. Populations also
seem to rise and fall in association with cliamte events, particularly El
Nino Southern Oscillation shifts in the Pacific. Given the extremely
small breeding range and the threat of the effects of climate change,
the IUCN lists the Heermann's Gull as "Near Threatened".
Photo Information: Photo taken on December 18th,
2008 - Pacific coast near San Francisco, California - Terry Sohl