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Species Database

Larus californicus - California Gull

California Gull image

Geographic range:

British Columbia, Canada to Baja California, Mexico

Key features:

In breeding plumage the combination of dark gray mantle, yellow green legs, and black and red spot on tip of lower mandible distinguish this species from all other gulls in its summer range.

Similar species:

Larus delawarensis -- Ring-billed Gull
Larus occidentalis -- Western Gull
Larus canus -- Mew Gull
Larus argentatus -- Herring Gull
Larus thayeri -- Thayer's Gull

Habitat(s):

bay (rocky shore), bay (sandy shore), estuary, exposed rocky shore, exposed sandy beaches, kelp forest, protected rocky shore, protected sandy beaches
 

Primary common name:

California Gull

General grouping:

Seabirds and shorebirds

ITIS code:

176829
 

Geographic Range

Range Description:

The California Gull is native to Mexico, Canada and the United States. It is common along the Pacific Coast in winter from Oregon southward, spending time in nearly every habitat found along the Pacific Coast. It is found inland in breeding season, nesting in large colonies on lakes, farms, and marshes on the prairies of western Canada, east to North Dakota, south to northwestern Wyoming and Utah, and west to northeastern California. It can survive in habitats that are too harsh for Herring and Ring-billed Gulls. It may be seen in any season in marine habitats and its range is fairly large, reaching up to 2 million square kilometers. It is also common off shore in late summer and fall.

Habitats

bay (rocky shore), bay (sandy shore), estuary, exposed rocky shore, exposed sandy beaches, kelp forest, protected rocky shore, protected sandy beaches

Habitat notes:

Broad range of habitats.

Abundance

Relative abundance:

Common

Species Description

General description:

This is a medium-sized gull (smaller than a Ring-billed Gull and larger than a Herring Gull) with the typical 'gull-like' appearance of slate-gray back and wings, white round head and body, and black wingtips with white spots. The black wingtips are larger than those of other gulls. Its eye is dark with a red orbital ring. Its legs and feet are greenish-yellow. The bill is yellow with a red and black spot near the tip on the lower mandible. Its voice is hoarse and scratchy, the tone is never clear. Its call is a series of long ‘kyow’ notes; the first two are longer and more drawn out. Call is higher pitched than corresponding call of the Herring Gull. It has a strong direct flight with deep wing beats and soars on thermals and updrafts.

There are two subspecies of California Gull. Those that breed in the Great Basin region (primarily Nevada and Utah) are smaller with darker backs. Those breeding in the northern Great Plains are larger and paler.

It takes four years for a California Gull chick to attain adult plumage. The first year juvenile plumage includes a dark brown head and body with the face and nape more pale. The back is brown with light edgings to the feathers. The throat, breast, belly, and undertail are barred gray-brown and white. The tail is black, edged in white. The flight feathers are blackish, the inner primaries and secondaries are gray-black. The entire juvenile bill is black, with the base getting lighter with time. The legs are brown to black and the eyes are dark brown.

The first winter bird is much like the juvenile, but the head, throat and breast are whiter and the back has become dusky gray with spots of brown. The belly is mostly white. Bill and eyes are like the juvenile stage. The first summer is much like the first winter plumage, with the wing feathers becoming worn and paler brown and the rump becoming white. The bill becomes pale with a black tip.

In the second winter the wing tips become black with head, throat, and belly mostly white and the back gray and mottled. The bill is creamy white with a black band near the tip. Legs change to bluish. The second summer plumage is much the same with white spots developing on the wing tips. The bill turns cream to greenish to yellow with a black band and the beginning of a red spot on the lower mandible. Legs and feet vary from cream to gray to greenish to yellow.

By the third winter California Gulls have grayish brown streaking on the back, with head and neck and underparts being white. The tail is mostly white and outer wing feathers are black with white spots. Third summer legs are light green and otherwise much like the third winter.

Finally by the fourth summer adult plumage is completed, which is very similar to the third summer.

Distinctive features:

The darker mantle and eyes, along with the black and red on the tip of the bill differentiates the California Gull from the smaller Herring Gull. The California Gull is also similar to Ring-billed Gull but larger, with a longer bill (also with red), dark eyes (the Ring-billed has pale eyes) and relatively long and narrow wings.

Size:

Length: 18.5-21.3 in (47-54 cm) Wingspan: 51.2 in (130 cm) to 54 in (137 cm) Weight: 15.2-36.9 oz (430-1045 g) Males are slightly larger than females

Natural History

General natural history:

The California Gull breeds in open habitats in the northern Great Basin, northern Intermountain Region and northern Great Plains, extending north to Canada. Colonies are nearly always on islands in natural lakes or rivers, or in reservoirs, which may be fresh and oligotrophic (containing relatively little plant life or nutrients, but rich in dissolved oxygen) or saline, saturated with dissolved salts. Colonies may be found from sea level to at least 2,770 m. Their nonbreeding range is usually similar to their breeding range except that they move toward the Pacific to marine habitats also, from waters at the edge of the continental shelf to beaches and rocky coasts, mudflats, coastal estuaries, and deltas of rivers and streams.

California Gulls return to breeding colony sites 3-7 weeks before egg laying, often when snow is still on the ground. Even at their northern sites they arrive as early as April, when temperatures are below zero and ice on lakes is thick. Mono Lake is home to the second largest California Gull rookery in North America (Great Salt Lake is the largest). By April, anywhere from 44,000 to 65,000 California Gulls arrive from winter haunts to breed on Mono's islands. Here, safe from land-based predators and humans, the gulls scratch out depressions in the rocky soil, decorate their chosen spot with sticks and feathers, and lay up to three black-speckled, khaki-colored eggs. Downy chicks hatch in June and fledge in July, following their parents back to their wintering grounds by early August. During the breeding period, the quiet of Mono's islands is shattered by the screams of gulls defending their nests against their neighbors, as they often nest within two feet of each other. The gulls nest so densely that you might find 4000 nests in an area the size of a football field! It is believed that coastal nesting occurs only at San Francisco Bay. Recently, a small nesting colony has also become established along the southern shores of the Salton Sea, California.

The California Gull is a common fall and winter resident in MBNMS area. Some are also present during spring and summer. The global population of the California Gull is thought to be between 500,000 and 1 million individual birds. It is reported that the wintering population in Monterey Bay area is >10,000 birds. The population in United States is estimated to have doubled since 1930. Increases are ongoing: for example, in San Francisco Bay, breeding California Gulls increased from <200 in 1982 to >46,800 in 2008.

Predator(s):

It is believed that few losses occur from predation, unless a predator creates enough disturbance to cause abandonment of nests. The fact that California Gulls are such voracious predators themselves, and that they nest close to each other in large colonies, means that they are able to fend off most predators. However disturbance by researchers can scare off parents exposing eggs or chicks to predation by other California Gulls.

Prey:

California Gulls are voracious predators and impact other nesting water birds by taking eggs and chicks and displacing colonies of other breeding water birds from preferred breeding sites. They are highly opportunistic and may eat small mammals, young chicks and eggs, fishes, insects, earthworms, grain, garbage, fruit, and a great variety of invertebrates. When foraging for food they may range as far as 60 km, taking them to alpine lakes and meadows, taiga (subarctic coniferous forest) bogs, irrigated fields, wet school yards, pastures, sagebrush and high-desert scrublands, rivers, lakes, weirs, irrigation canals, sloughs, garbage dumps, sewage canals, treatment ponds, feed lots, orchards, and well off shore (but usually not >10 miles from shore). Their only requirement seems to be that the foraging area be fairly open, not in densely vegetated fields or orchards. They may pirate food from other species and follow ships and fishing boats. At Mono Lake they feed on trillions of brine shrimp.

Feeding behavior

Omnivore

Feeding behavior notes:

The California Gull, like most gulls, is an opportunistic feeder, eating anything it can catch or scavenge. It has an odd foraging strategy for catching alkali flies along the shores of salty lakes in the Great Basin. It starts at one end of a huge raft of flies sitting on the beach and runs through the flies with its head down and bill open, snapping up flies. It will dip for prey items on the surface of the water and use a variety of foraging strategies, feeding while walking, wading, swimming, or flying. They are often seen on farms or in fields, following behind the plows and picking up insects uncovered by the machinery. They have also been reported to lie in wait for rodents to be flooded out of their holes when fields are irrigated.

The California Gull is the 'seagull' that came to the aid of Mormon settlers in Utah in 1848, helping rid their crops of a plague of grasshoppers. Thus Utah claims the California Gull as its state bird. The California Gull is still considered a beneficial species throughout its range, although it has been associated with some crop damage.

February - May

Migration:

Adults leave their wintering areas along the Pacific Coast beginning in February. Those further north leave later. When they arrive on their breeding grounds on the northern Great Plains in March or April snow is still covering their nesting sites. Subadults or adults skipping breeding often remain in wintering areas during the breeding season.

April - July

Reproduction:

Breeding occurs throughout the interior western region of North America from Mono Lake, California, to Lac la Martre, Northwest Territories and as far east as western Manitoba. It is believed that a breeding colony has started in evaporation ponds in the San Francisco Bay area. In much of their breeding range they mix with Herring Gulls and Ring-billed Gulls, but seldom hybridize with either.

Newly formed pairs select their nesting site together by walking around the area and giving mewing calls and a 'choking display', which involves the pair rushing toward another pair of gulls, bending the legs, lowering the body and pointing the bill as if to peck the ground. The head is jerked rapidly while uttering a guttural 'hoh hoh hoh' sound. The birds are monogamous for the duration of the breeding season. Their preferred sites include isles, open sand or gravel with scattered grass, or along lake or pond shores. Nest building by the pair begins when their territory is established and consists of digging a scrape and lining it with sticks, dried weeds, rubbish, and feathers. Old pairs often return to their site from previous years. The nests are close to each other in large colonies. Egg laying will begin about one week after the onset of nest building. Generally an egg is laid every other day until the clutch is complete (2-3 eggs, usually). They are brown/olive/gray/olive buff marked with dark brown/gray. They are large at 2.7 inches (6.8 cm). Both parents incubate the eggs for about 3.5 weeks, taking turns in about three hour intervals. When they exchange places there is much calling and strutting around their territory. The young leave the nest after a few days, but stay nearby and are fed regurgitated food by their parents until they can fly when they are about 6.5 to 7 weeks old.

A second brood is not attempted unless first clutch is destroyed.

July - September

Migration:

Fledglings generally move directly toward the Pacific coast at the end of breeding season, while many adults linger at the colony site and aquatic habitats as long as food is available, giving them time to rejuvenate before migrating. It is believed that they do not form a special flock formation, but move in loose bands, and travel silently without calls.

August - March

Feeding:

Rather than having a distinct wintering area, California Gulls move slowly up and down the Pacific Coast, a large winter range. It appears that younger birds move longer distances, and also males farther than females. Some remain in their breeding range during winter, including MBNMS and Flathead Lake, MT. The availability of garbage and open water in many inland areas makes over-wintering possible.

Listing Status:

IUCN status: Least Concern The population of California Gulls has increased over the past 100 years. They are susceptible to human and animal disturbances at their nesting sites and to degradation of suitable habitat. The ingestion or entanglement in plastic, while foraging at garbage dumps or landfills, may be a source of mortality.

Monitoring Trends:

Population has been increasing along the central coast since the 1980s.
Ehrlich, P., D.S. Dobkin, and D. Wheye. 1988. The Birders Handbook: A Field Guide to the Natural History of North American Birds. Simon & Schuster Inc., New York. 785 p.
Pugseek, B.H., K.L. Diem, and C.L. Cordes. 1999. Seasonal movements, migration and range sizes of subadult and adult Bamforth Lake California Gulls. International journal of Waterbird Biology 22(1): 29-36.
Roberson, D. 2002. Monterey Birds 2nd edition. Monterey Peninsula Audubon Society, Carmel, CA. 536 p.
Sibley, D.A. 2000. The Sibley Guide to Bird. Alfred A. Knopf, Inc. 545 p.
WWW
Birds of North America Online
http://bna.birds.cornell.edu/bna
Accessed 09/10/2009 for Eared Grebe
Accessed 06/20/2010 for Black Turnstone

WWW
BirdWeb
http://birdweb.org/birdweb/
Accessed 08/30/2010 for Ruddy Turnstone
Accessed 10/10/2010 for Pacific Loon
Accessed 12/04/2010 for Bufflehead
Accessed 02/20/2011 for Western Sandpiper

WWW
Cornell Lab of Ornithology
All About Birds
http://www.allaboutbirds.org/guide/search
Accessed 05/17/2009 for Albatross
Accessed 01/15/2009 for Clark's Grebe
Accessed 01/20/2009 for Great Egret
Accessed 02/03/2009 for American White Pelican
Accessed 01/30/2009 for Pelagic Cormorant
Accessed 02/12/2009 for Black-necked Stilt
Accessed 02/28/2009 for Marbled Godwit
Accessed 03/15/2009 for Whimbrel
Accessed 04/11/2009 for Long-billed Curlew
Accessed 04/13/2009 for Heermann’s Gull
Accessed 09/10/2009 for Eared Grebe
Accessed 11/11/2009 for American Avocet
Accessed 01/26/2010 for Pigeon Guillemot
Accessed 12/15/2009 for Black-crowned Night Heron
Accessed 07/07/2009 for Pied-billed Grebe
Accessed 04/04/2010 for Osprey
Accessed 08/30/2010 for Ruddy Turnstone
Accessed 10/10/2010 for Pacific Loon
Accessed 10/15/2010 for Sooty Shearwater
Accessed 10/30/2010 for Surf Scoter
Accessed 12/04/2010 for Bufflehead
Accessed 02/01/2011 for American Coot
Accessed 02/20/2011 for Western Sandpiper
Accessed 03/04/2011 for Least Sandpiper.
Accessed for California Condor

WWW
Mono Lake Org.
http://www.monolake.org/images/bomgull.pdf
PDF
WWW
National Geographic
Animal Database
http://animals.nationalgeographic.com/animals/birds/great-egret.html
Accessed 01/25/2009 for Great Egret
Magazine. 2009.
http://ngm.nationalgeographic.com/2006/06/pelican-grace/white-text/2
Accessed 2/03/09 for American White Pelican
Accessed 04/04/2010 for Osprey
Accessed for California Gull
Accessed for California Condor

WWW
USGS Western Ecological Research Center (WERC)
http://www.werc.usgs.gov/Project.aspx?ProjectID=184
Accessed for California Gull
WWW
WhatBird.com. Field Guide to Birds of North America.
http://www.whatbird.com
Accessed 12/30/2008 for Black-footed Albatross
Accessed 01/30/2009 for Pelagic Cormorant
Accessed 02/28/2009 for Marbled Godwit
Accessed 04/14/2009 for Willet
Accessed 04/13/2009 for Heermann’s Gull
Accessed 09/10/2009 for Eared Grebe
Accessed 06/20/2010 for Black Turnstone
Accessed 12/15/2009 for Black-crowned Night Heron
Accessed 10/13/2009 for Horned Grebe
Accessed 10/10/2010 for Pacific Loon
Accessed 10/30/2010 for Surf Scoter
Accessed 02/01/2011 for American Coot
Accessed 02/20/2011 for Western Sandpiper
Accessed 03/04/2011 for Least Sandpiper.