There are traces of human occupation in the islands since the Iron Age. Ceramics have also been found since Roman times. The islands were occupied by various monastic orders during the Middle Ages, were owned by the Church, gauged by nobles of the time and attacked by invaders who used them as a base for raids on the coast. More recently, the Cíes Islands were inhabited until the eighteenth century, but by pirates' action, people had to abandon the islands. Ons Island is still home to a small permanent population of 63 people. In 1980 the Cíes Islands were declared a natural park. They are also a "Special Protection Area" for birds. On June 13, 2002 was declared a national park. However, 6 months later, the oil spill caused by the Prestige oil tanker came on its shores, except on the island of Cortegada. The islands of Lobeiras and Sisargas were initially discussed to be part of the national park and could be added to the park in the future.