"Sterna forsteri. Forster's Tern. Tail 5.00 - 8.00, forked 2.50-5.00." Elliot Coues, 1884

Tail of Forster's Tern

"Sterna forsteri. Forster's Tern. Tail 5.00 - 8.00, forked 2.50-5.00." Elliot Coues, 1884