Saunders's Tern vs Gull-billed Tern

Saunders's Tern and Gull-billed Tern can be distinguished by size and bill shape. Saunders's is smaller with a slender, straight bill, while Gull-billed is larger and has a short, heavy black bill. Both have black caps in breeding plumage, but their size difference is a key field mark.

1. Size: Saunders's Tern is noticeably smaller. 2. Bill Shape: Saunders's has a slender, straight bill; Gull-billed has a short, heavy black bill. 3. Habitat: Note the habitat; Gull-billed is more versatile. 4. Behavior: Observe feeding behavior; Saunders's often hovers before diving, while Gull-billed forages over land. 5. Vocalization: Listen for the call; Saunders's is high-pitched, Gull-billed is guttural.

Saunders's Tern is smaller, typically around 23–25 cm in length, while the Gull-billed Tern is medium-sized, measuring 33–38 cm.

Saunders's Tern has a more delicate appearance with a slender, straight bill and a black cap during breeding. Gull-billed Tern has a stockier build with a short, heavy black bill and a black cap in alternate plumage. In non-breeding plumage, Gull-billed Tern lacks the black cap but may have a dark smudge behind the eye.

Saunders's Tern often hovers before diving for fish, typical of smaller terns. Gull-billed Tern is less likely to dive, often seen foraging over land for insects.

Saunders's Tern is typically found in coastal areas and sandy beaches. Gull-billed Tern can be found in a wider range of habitats, including inland wetlands and coastal areas.

Saunders's Tern has a high-pitched, sharp call. Gull-billed Tern's call is more guttural and less sharp.