California Gull Identification Guide

Key Field Marks

• Size & shape: Medium-large gull, distinctly smaller and more slender-billed than a Herring Gull but larger than a Ring-billed Gull, with a fairly rounded head and moderate-length bill.
• Adult plumage: Medium gray back and upperwings, white head and underparts (streaked with brown in nonbreeding/winter plumage), black wingtips with white spots.
• Bill: Yellow bill with both a black spot and a red spot near the tip of the lower mandible - a key mark separating it from Ring-billed Gull, which shows only a black ring/spot.
• Legs: Greenish-yellow to yellow legs, duller and less bright than the legs of a Ring-billed Gull.
• Eye: Dark eye with a fairly obvious dark red-orange orbital ring in breeding adults.
• Immatures: Multi-year plumage progression through mottled brown first-winter birds to gray-backed subadults, typical of large gulls; leg and bill pattern combined with structure help narrow down age classes.

Separating from Similar Species

• Ring-billed Gull: Smaller and daintier, with a pale eye and a bill showing only a single black ring (no red spot), and brighter yellow legs.
• Herring Gull: Larger and bulkier, with pink (not yellow) legs and a heavier bill, plus a paler gray back.
• Mew Gull: Smaller still, with a shorter, more delicate unmarked yellow-green bill and rounder head.
• Structure tip: California Gull's bill looks proportionally longer and more slender than Ring-billed Gull's, an important supporting clue alongside the leg and bill-spot differences.

Where & When to See It

• Habitat: Breeds colonially on islands in large interior lakes, alkaline lakes, and reservoirs of the western interior; winters along the Pacific Coast on beaches, bays, estuaries, and parking lots/landfills.
• Range: Breeding range spans the Great Basin and northern Great Plains (e.g., Great Salt Lake, Mono Lake); winters from British Columbia south to Mexico along the Pacific coast.
• Season: Present at interior breeding colonies spring through late summer; most common along the coast in fall, winter, and early spring.

Voice & Behavior Cues

• Calls include a range of typical large-gull notes - a bugling, laughing kee-ow and shorter barking calls given in flight and at colonies.
• Highly social; forms large nesting colonies on islands and mixes readily with other gull species at coastal roosts and foraging areas, making direct side-by-side comparison useful for identification.