How to identify the Gull

To correctly identify the Gull (Larus), 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

25-79 cm (10-31 in)

Wingspan

61-170 cm (24-67 in)

Weight

100-2000 g (3.5 oz - 4.4 lbs)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Adult plumage typically features a white head and underparts, a grey or black mantle (back and upperwings), and black wingtips often with white 'mirrors'. Juvenile plumage is usually mottled brown or grey, transitioning through several immature stages over 2-4 years to reach adult coloration. Specific patterns vary significantly between species.

2. 2

   Beak shape

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

   Strong, slightly hooked, and often brightly colored (yellow, orange, red) with a gonydeal angle (a prominent bulge on the lower mandible). Bill color can vary with age and season.

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Usually dark, but can be pale yellow or reddish in some species, often with a distinct orbital ring (red, yellow, or orange).

4. 4

   Leg color

   Leg and foot color.

   Typically yellow, pink, or reddish, varying by species and age. Some species have dark legs.

5. 5

   Distinguishing features

   Standout features that separate this species.

   General gull shape, long wings, webbed feet. Species-specific features include mantle color (light grey to black), head pattern (hooded, white, streaked), bill size and color, leg color, and wingtip patterns (extent of black, presence/absence of white mirrors).

6. 6

   Juvenile appearance

   How young birds differ from adults.

   Highly variable and complex. Juveniles are typically mottled brown or grey, often with dark bills and legs. They undergo several molts, gradually acquiring adult-like plumage over 2-4 years, making age determination challenging and species identification difficult without experience.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   Many species exhibit seasonal plumage changes. Breeding plumage often features a clean white head (e.g., Herring Gull) or a dark hood (e.g., Black-headed Gull). Non-breeding plumage typically involves streaking or smudging on the head and nape, and sometimes duller bill/leg coloration.

8. 8

   Sexual dimorphism

   How males and females differ.

   Generally minimal, with males often slightly larger than females, but plumage is typically identical. Size differences are usually subtle and not reliable for field identification.

Key field marks

• Size and Shape. Observe overall size (small, medium, large) and body proportions (slender vs. robust). This helps narrow down possibilities significantly.
• Mantle Color. Note the color of the back and upperwings. This ranges from very pale grey (e.g., Glaucous Gull) to medium grey (e.g., Ring-billed Gull) to dark grey (e.g., Lesser Black-backed Gull) to black (e.g., Great Black-backed Gull).
• Leg Color. Check leg color: pink, yellow, greenish-yellow, or dark. This is a crucial field mark for many species, especially adults.
• Bill Color and Markings. Note the bill color (yellow, orange, red, dark) and any distinct markings, such as a black ring, a red spot (gonydeal spot), or a dark tip. Bill size and robustness are also important.
• Head Pattern (Adults). Observe if the head is clean white, streaked with grey/brown (non-breeding), or has a full dark hood (breeding). The extent and color of streaking can be diagnostic.
• Wingtip Pattern. Examine the pattern of black and white on the primary wingtips. This is often highly species-specific, including the extent of black, the presence and size of white 'mirrors' (spots), and the pattern of white trailing edges.
• Juvenile/Immature Plumage. Be aware that gulls take 2-4 years to reach adult plumage. Immature birds are often mottled brown/grey and can be very challenging to identify. Look for overall tone, bill color, and any emerging adult-like features.
• Vocalizations. Learn the distinctive calls of common species in your area. The 'long call' is particularly useful for identification.

Explore the Gull