Regular migrant in small numbers, most records having been from the south of Isabela Island and Santa Cruz Island from January to March. Breeds in North America, the Caribbean and northern South America, some birds migrating to winter along the north-west coast of South America.
A large, stocky tern with a heavy, orange bill and black legs. ADULT BREEDING: Upper parts pale gray; under parts white. Black crown, extending from bill to nape. In flight shows white forked tail and dark trailing-edge to primaries on under wing. ADULT NON-BREEDING: Similar to adult breeding but lores, forehead and forecrown white, merging with variable black spotting on crown, to shaggy black nape. FIRST-WINTER: Resembles non-breeding adult, but has dark brown markings on wings.
A loud, harsh "kee-reer'
Could be mistaken for a Galapagos gull due to its large size and powerful flight. When feeding, flies relatively high over the water and plunge-dives or surface-dips.