Forster's Tern vs Arctic Tern

In short

Forster's Tern and Arctic Tern can be distinguished by their tail length and plumage details. Forster's Tern has a longer tail with a more deeply forked appearance, while Arctic Tern has a shorter tail relative to its body. In breeding plumage, Forster's Tern shows a distinctive black cap and pale gray upperparts, whereas Arctic Tern has a more uniform gray body and a black cap that extends further down the nape.

Identification tips

1. Tail Length: Forster's Tern has a longer, more deeply forked tail. 2. Plumage: In breeding season, check for the extent of the black cap and uniformity of gray on the body. 3. Habitat: Note the surrounding environment; marshes suggest Forster's Tern, open water suggests Arctic Tern. 4. Vocalization: Listen for the harsh call of Forster's Tern compared to the more musical call of Arctic Tern.

Size

Forster's Tern is slightly larger and more robust than Arctic Tern, with a longer tail and wings.

Plumage

Forster's Tern in breeding plumage has a black cap and pale gray upperparts, with a white underbody. Arctic Tern also has a black cap but is more uniformly gray across the body. In non-breeding plumage, Forster's Tern has a white forehead, while Arctic Tern retains a more uniform head pattern.

Behaviour

Both species exhibit similar flight patterns typical of terns, but Forster's Tern is more often seen foraging over marshes, while Arctic Tern is typically seen over open water.

Habitat

Forster's Tern is primarily a marsh bird, found in fresh, brackish, and saltwater marshes. Arctic Tern is more associated with open oceans and coastal areas, especially during migration.

Voice

Forster's Tern has a distinctive harsh call, while Arctic Tern's call is higher-pitched and more musical.