Larus californicus
(California Gull)

Physical Description:
20-23" (51-58 cm). Adults have white head, underparts, and tail; back and wings dark gray; wing tips black with large white spots; red and black spot on the lower mandible; dark eyes with reddish eye-ring; legs yellow-green. Immatures mottled with brown both above and on underparts; tail mostly all dark; bill gray-pink with subterminal black bar; legs pinkish; lack eye-ring.

Similar Species- Herring and Ring-billed Gulls

Song:
A shuddering, repetitive kee-yah.

Distribution:
Breeds from parts of western Canada, south to east-central North Dakota, central Montana, northwestern Wyoming, eastern Idaho, northwestern Utah, Northwestern Nevada, eastern California, southeastern Oregon, and southern Washington. Winters from southern Washington and eastern Idaho, south along Pacific Coast to southern Baja California and northwestern mainland Mexico.

Habitat:
Found on seacoasts, bays, estuaries, mudflats, marshes, irrigated fields, lakes, ponds, dumps, agricultural lands, and in cities.

Diet:
In inland areas, feeds on mice and insects (crickets, grasshoppers, and cutworms). Along the coast, feeds on dead fish and garbage; scavenges behind boats and around harbors and dumps.

Ecology:
Builds nest in depression on ground; in Idaho, nests are typically on islands. May gather in large flocks, often in association with Ring-billed or other gulls. Species is colonial; colony size in Idaho averages about 4000 nests. Although Great Horned Owl may cause significant mortality in breeding colony, colonial waterbird surveys conducted between 1984 and 1994 indicate that California Gull numbers have increased three-fold during this time period.

Breeding begins in late April in southern range, to early June in north. Both sexes incubate 3 eggs for 23-27 days (2.2-2.6 eggs in Idaho). Nestlings are semi-precocial and downy. Young are tended by both parents. Adults may form female-female pairs.

Conservation:

Element Code:	ABNNM03110
Status:	Protected nongame species
Global Rank:	G5
State Rank:	S3
National Rank:	N5B,N5N

Important State References:
Trost, C.H. and A. Gerstell. 1994. Status and distribution of colonial nesting waterbirds in southern Idaho, 1993. Dept. Biol. Sciences, Idaho St. Univ., Pocatello. 101pp.