Great Black-backed Gull vs Glaucous Gull

In short

The Great Black-backed Gull and Glaucous Gull are large gulls that can be distinguished by their size and plumage. The Great Black-backed Gull is the largest gull in the world with a striking black back, while the Glaucous Gull is slightly smaller and lacks black in its plumage, appearing pale overall.

Identification tips

1. Size: Look for the larger size and bulk of the Great Black-backed Gull. 2. Plumage: Note the black back of the Great Black-backed Gull versus the pale, unmarked appearance of the Glaucous Gull. 3. Location: Consider the habitat; the Glaucous Gull is more likely in northern, tundra regions. 4. Behavior: Observe interactions; the Great Black-backed Gull is often more dominant.

Size

The Great Black-backed Gull is larger and bulkier than the Glaucous Gull, making it the largest gull species.

Plumage

The Great Black-backed Gull has a distinctive black back and wings, contrasting with its white body. The Glaucous Gull, in contrast, is pale throughout with no black markings, appearing almost entirely white or light gray.

Behaviour

Both species are opportunistic feeders, but the Great Black-backed Gull often dominates other gulls due to its size. The Glaucous Gull is also a generalist feeder but is less aggressive.

Habitat

The Great Black-backed Gull typically nests on islands and coastal areas, while the Glaucous Gull is found in more northern habitats, including tundra and high coastal cliffs.

Voice

Vocalizations of both species are similar, consisting of typical gull-like calls, but specific differences are not well-documented.