Great Black-backed Gull vs California Gull

In short

The Great Black-backed Gull is notably larger and bulkier than the California Gull, with a striking black back and wings. In contrast, the California Gull is smaller, with a lighter gray back and more slender build. Observing size and plumage are key to distinguishing these species in the field.

Identification tips

• Size and bulk: Great Black-backed Gull is much larger and bulkier.
• Back color: Great Black-backed Gull has a black back; California Gull has a gray back.
• Bill: Great Black-backed Gull has a thicker bill.
• Habitat: Consider location; Great Black-backed Gulls are more coastal.
• Vocalization: Listen for deeper calls from Great Black-backed Gulls.

Size

The Great Black-backed Gull is the largest gull species, significantly larger and more robust than the medium-sized California Gull.

Plumage

Great Black-backed Gulls have a distinctive black back and wings, while California Gulls have a lighter gray back. Both species have white underparts, but the Great Black-backed Gull's darker upperparts are a key identifier.

Behaviour

Both species are opportunistic feeders, but the Great Black-backed Gull often dominates due to its size, displacing other gulls from feeding sites.

Habitat

Great Black-backed Gulls are typically found in coastal areas, often nesting on islands or offshore rocks. California Gulls are more versatile, found in both coastal and inland habitats, including lakes and rivers.

Voice

Vocalizations are not the primary means of distinguishing these species, as both have typical gull calls. However, the Great Black-backed Gull's calls are deeper and more resonant.