Western gull Larus occidentalis

Identification Tips:

• Large gull
• Fairly large bill with distinct gonydeal angle
• Flat forehead and large bill give "mean" appearance

Adult alternate:

• Bright yellow bill with red spot at gonys
• Pink legs
• Yellow iris
• White head, neck, breast, and belly
• Dark gray back and upperwings (paler in northern birds)
• White tertial and scapular crescent
• Black primaries with white tips and a single white mirror on outermost primary
• White tail

Adult basic:

• Like adult alternate but has faint brown streaking on head

Juvenile/First-year:

• Black bill
• Wholly brown body plumage
• Dark brown primaries and secondaries
• Black legs quickly become pink
• Dark tail
• Whitish rump contrasts with dark back

Second-year:

• Pinkish bill with black tip
• Pale head, neck, upper breast, and belly
• Dull brown upperwing coverts
• Dark brown primaries and tail
• Dark gray back

Third-year:

• Like adult basic, but often lacks adult bill pattern, wing pattern, and often retains a partial tail band

Similar species:

Adult Western Gulls are dark-backed enough to prevent confusion with Herring, Ring-billed, Glaucous-winged, Thayer's, and California gulls. The Yellow-footed Gull of southern California is nearly identical except that it has yellow rather than pink legs and is a three-year gull rather than a four-year gull and thus shows a different plumage progression. Otherwise the Western Gull does not overlap in range with Great or Lesser Black-backed Gulls, but might be separable from both by shape, leg color, and mantle color. Beware of intermediately-colored Glaucous-winged x Western Gull hybrids, which should show larger bills than typical Western Gulls.