The Trinidade Petrel, Pterodroma arminjoniana, is a species of seabird and a member of the gadfly petrels. The bird is 35-39 cm in size, with a 88-102 cm wingspan.
The petrel has 2 color morphs, a dark phase and a light phase, with intergrades between the two also occurring. There are also 2 separate populations, one occurring in the south Pacific, sometimes seen in Hawaii; the other occurring in the south Atlantic, nesting off Brazil, with rare sightings in the Gulf Stream off the southeastern United States. The little-known Pacific subspecies Pterodroma (arminjoniana) heraldica may be a distinct species (Herald Petrel). It uses oceanic islands, atolls, nesting on cliff ledges, ridges or rocky slopes. On some islands, nesting birds are threatened by feral cats and rats.
Due to ongoing habitat lost and small breeding range, this species is evaluated as Vulnerable on the IUCN Red List of Threatened Species.
In May 2007, a Herald Petrel tagged on Raine Island in 1984 was observed off the coast of Mauritius in the Indian Ocean. This greatly increases the known life span and range of the species.