It is the largest gannet-nesting colony in the world.
The former is a species of gannet, and the latter a tern.
In spite of its hostile environment, the island is host to a number of bird species including a gannet colony.
British Dictionary definitions for gannet
any of several heavily built marine birds of the genus Morus (or Sula), having a long stout bill and typically white plumage with dark markings: family Sulidae, order Pelecaniformes (pelicans, cormorants, etc) See also booby (sense 3)
(slang) a gluttonous or greedy person
Old English ganot; related to Old High German gannazzo gander
Old English ganot "gannet, sea-bird, water fowl," from Proto-Germanic *ganito (cf. Dutch gent, Middle High German ganiz, Old High German ganazzo), from PIE *ghans- (see goose). Old French gante is from Germanic.