Slender-billed Gull vs Sooty Gull

In short

The Slender-billed Gull is best distinguished by its long, thin bill and more delicate structure compared to the Sooty Gull, which has a heavier, thicker bill. In flight, the Slender-billed Gull's wings appear more elongated and slender, while the Sooty Gull shows a darker mantle and wingtips.

Identification tips

• Bill Shape: Look for the long, slender bill of the Slender-billed Gull versus the thicker bill of the Sooty Gull.
• Plumage: Note the paler plumage of the Slender-billed Gull, especially the white head, compared to the darker head and mantle of the Sooty Gull.
• Wing Shape: In flight, the Slender-billed Gull's wings are more elongated and slender.
• Habitat: Consider the habitat; Slender-billed Gulls are more often found in lagoons and estuaries, while Sooty Gulls are more coastal and marine.
• Behavior: Observe foraging behavior; Slender-billed Gulls may forage in shallower waters.

Size

The Slender-billed Gull is generally more delicate and slender in appearance, while the Sooty Gull is bulkier.

Plumage

Slender-billed Gulls have a paler overall plumage with a white head and underparts, whereas Sooty Gulls have a darker head and mantle, especially noticeable in breeding adults.

Behaviour

Both species can be seen in coastal environments, but the Slender-billed Gull often forages in shallower waters and is more likely to be seen inland.

Habitat

The Slender-billed Gull is often found in coastal lagoons and estuaries, while the Sooty Gull prefers coastal and marine environments, often near harbors and beaches.

Voice

Vocalizations are not the most reliable differentiator in the field; both species have typical gull-like calls.