How to identify the Western Gull

To correctly identify the Western Gull (Larus occidentalis), check each of these features. Birds can be tricky: habit, habitat, and call often confirm a sighting that a single photo cannot.

Size at a glance

Length

58-66 cm (23-26 in)

Wingspan

130-144 cm (51-57 in)

Weight

800-1400 g (1.8-3.1 lbs)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Adults have a dark slate-gray to blackish mantle and wings, contrasting with white head, neck, underparts, and tail. The wingtips are black with small white mirrors. Juveniles are mottled brown, gradually acquiring adult plumage over 3-4 years.

2. 2

   Beak shape

   Shape and color of the bill: a key field mark.

   Large, heavy, yellow bill with a prominent red spot on the gonys (lower mandible).

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Pale yellow with a dark orbital ring.

4. 4

   Leg color

   Leg and foot color.

   Pink.

5. 5

   Distinguishing features

   Standout features that separate this species.

   Large size, dark mantle (darker than most other large gulls in its range), pink legs, and heavy yellow bill with a red spot. The dark orbital ring around the pale eye is also a good field mark.

6. 6

   Juvenile appearance

   How young birds differ from adults.

   First-year birds are dark brown overall, heavily mottled, with a dark bill and dark legs. They gradually lighten and acquire adult features over several molts, becoming paler brown in their second year, and showing more gray in their third year.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   No significant seasonal plumage changes in adults, though non-breeding adults may have faint streaking on the head and nape. Breeding adults have a clean white head.

8. 8

   Sexual dimorphism

   How males and females differ.

   Males are typically slightly larger and heavier than females, but plumage is identical.

Key field marks

• Mantle Color. Look for the very dark slate-gray to blackish mantle (back and upper wings). This is a key distinguishing feature from most other large gulls in its range.
• Leg Color. Observe the legs, which are consistently pink in adults. This helps differentiate from species with yellow or greenish legs.
• Bill. Note the large, heavy yellow bill with a prominent red spot on the lower mandible (gonys). The size and color are distinctive.
• Eye Color. Adults have a pale yellow eye surrounded by a dark orbital ring, which contrasts with the dark eye of many other gull species.
• Wingtips. The wingtips are black with small white 'mirrors' (spots). This contrasts with the pale gray wingtips of Glaucous-winged Gulls.
• Size and Build. Western Gulls are large and robust, giving them a powerful appearance compared to smaller gull species.

Explore the Western Gull