The small, rocky islands that are situated off the shore of Easter Island host a significant population of sea birds including seagulls, frigate birds and the legendary black tern, which has become very rare today, but played a very essential role in the island's belief of a man-bird beast. Every year, when this migratory bird known under the Indian name of manutara used to arrive, men would go offshore Motu Nui Island in the aim of bringing back one of its eggs. The first to accomplish the task would allow the chief of his tribe to be crowned the man-bird.