Sooty Tern vs Gull-billed Tern

In short

The Sooty Tern and Gull-billed Tern can be distinguished by their bill shape and plumage. The Sooty Tern has a slender, pointed bill and a striking black-and-white plumage, while the Gull-billed Tern has a stout, heavy black bill and overall paler appearance.

Identification tips

1. Bill shape: Sooty Tern has a slender, pointed bill; Gull-billed Tern has a short, heavy black bill. 2. Plumage: Look for the bold black-and-white contrast in Sooty Tern versus the paler gray and white of the Gull-billed Tern. 3. Behavior: Sooty Terns are almost always in flight; Gull-billed Terns may be seen resting. 4. Habitat: Sooty Terns are typically over open oceans; Gull-billed Terns can be found in a variety of wetland habitats.

Size

Both species are medium-sized terns, but the Gull-billed Tern is slightly larger and stockier.

Plumage

Sooty Tern has a bold black cap and back with white underparts, while the Gull-billed Tern has a black cap only in breeding plumage and is otherwise pale gray above and white below. Juvenile Gull-billed Terns have brown splotches on the upperparts.

Behaviour

Sooty Terns are almost always seen in flight, rarely resting on water, while Gull-billed Terns can be seen both flying and resting. Sooty Terns feed by dipping or snatching fish midair, whereas Gull-billed Terns often forage over land.

Habitat

Sooty Terns inhabit tropical and subtropical oceans, nesting on remote islands. Gull-billed Terns are more versatile, found in coastal and inland wetlands.

Voice

Vocalizations are not detailed in the sources, but Sooty Terns are known for their harsh, grating calls, while Gull-billed Terns have a more mellow, chuckling call.