These 19 species of this group of medium-sized birds consists of seven Prions, five Diving-petrels two Bulweria petrels and five species that are each in their own genus: the Blue, Kerguelen, Cape, Snow and Antarctic Petrel. The most recently recognised species is MacGillivary’s Prion (Pachyptila macgillivrayi) has a highly restricted distribution. Most of the population breeds on Gough Island in the South Atlantic, with a small population also breeding on Roche Quille, a rocky stack near Île Saint-Paul in the French Southern Territories. On Gough, breeding success is regularly close to zero, due to predation of the chicks by invasive house mice. Conservation efforts for this Endangered species focus should therefore focus on eradicating invasive mice from Gough Island.