Slaty-backed Gull vs Iceland Gull

In short

The Slaty-backed Gull and Iceland Gull can be difficult to distinguish, especially in non-breeding plumages. The Slaty-backed Gull is generally larger with a darker mantle, while the Iceland Gull is smaller with a paler, more uniform appearance. Key differences include mantle color and primary feather patterns.

Identification tips

1. Check mantle color: Slaty-backed Gulls have a darker slate-gray mantle. 2. Examine primary feathers: Look for dark wingtips with white 'mirrors' on Slaty-backed Gulls. 3. Consider size and bulk: Slaty-backed Gulls are larger and bulkier. 4. Observe location: Slaty-backed Gulls are more common in the North Pacific, while Iceland Gulls are found in the North Atlantic.

Size

The Slaty-backed Gull is larger and bulkier compared to the smaller, more delicate Iceland Gull.

Plumage

Slaty-backed Gulls have a dark slate-gray mantle and wingtips with white 'mirrors' on the primaries, whereas Iceland Gulls have a pale gray mantle and lack the dark wingtips, often appearing more uniformly pale.

Behaviour

Both species exhibit similar gull-like behaviors, such as scavenging and opportunistic feeding, making behavior a less reliable distinguishing factor.

Habitat

Slaty-backed Gulls are typically found in coastal areas of the North Pacific, while Iceland Gulls are more associated with Arctic and sub-Arctic regions, often seen in winter along the North Atlantic coasts.

Voice

Vocalizations are similar between the two species, with typical gull calls, making them unreliable for differentiation.