Distribution / Range
They live in the tropical oceans; in Mexico, the Caribbean and west Africa; around the Arabia and in Southeast Asia and Australasia. Rare vagrants western Europe.
This is a medium-sized tern, at 30–32 cm in length and with a 77–81 cm wingspan.
The wings and deeply forked tail are long, and it has dark grey upperparts and white underparts. The forehead and eyebrows are white, as is a striking collar on the hindneck. It has black legs and bill.