How to identify the Ring-billed Gull

To correctly identify the Ring-billed Gull (Larus delawarensis), 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

40-49 cm (15.7-19.3 in)

Wingspan

105-117 cm (41.3-46.1 in)

Weight

300-700 g (10.6-24.7 oz)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Adults have a white head, body, and tail, with a pale gray back and upperwings. The primary wingtips are black with white spots (mirrors).

2. 2

   Beak shape

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

   Medium-sized, relatively slender, yellow bill with a prominent black ring near the tip in adults. Juveniles have a pinkish bill with a dark tip, which gradually develops the black ring.

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Pale yellow with a red orbital ring in adults. Dark in juveniles.

4. 4

   Leg color

   Leg and foot color.

   Yellow in adults, pinkish-yellow in immatures.

5. 5

   Distinguishing features

   Standout features that separate this species.

   The most distinctive feature is the black ring on the yellow bill of adults. Also note the pale gray mantle, yellow legs, and pale yellow eyes.

6. 6

   Juvenile appearance

   How young birds differ from adults.

   Juveniles are mottled brown and white overall, with a dark brown bill and dark eyes. They undergo several molts, gradually acquiring adult plumage over 2-3 years. First-winter birds are largely brown-backed with a dark tail band and a pinkish bill with a dark tip. Second-winter birds are paler, with more gray on the back and a more defined black bill ring.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   Adults show very little seasonal variation. In breeding plumage, the head is pure white. In non-breeding plumage (winter), adults may develop faint dusky streaking on the head and nape, but the overall appearance remains largely the same.

8. 8

   Sexual dimorphism

   How males and females differ.

   Males and females are outwardly similar in plumage and size, though males tend to be slightly larger on average.

Key field marks

• Bill Markings. Look for the distinct black ring near the tip of the yellow bill in adult birds. This is the most reliable field mark.
• Leg Color. Adults have bright yellow legs. This distinguishes them from larger gulls with pink legs (e.g., Herring Gull) and some other medium-sized gulls.
• Size and Build. Medium-sized gull, smaller than a Herring Gull but larger than a Bonaparte's Gull. It has a relatively slender build compared to larger gulls.
• Plumage (Adult). White head, body, and tail, with a pale gray back and upperwings. Black primary wingtips with white 'mirrors'.
• Juvenile Plumage. Young birds are mottled brown and white, with a dark bill and dark eyes. They gradually acquire adult plumage over 2-3 years, so look for intermediate stages with varying amounts of brown and gray.
• Behavior. Often seen in large flocks, especially in urban areas, parking lots, and landfills, scavenging for food. Their opportunistic feeding behavior is a good clue.

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