The Tangata Manu or Birdman ceremony probably initiated in the 18th century in honor of the Make Make god and lasted until the arrival of the Catholic missionaries in 1866. The main event of this ceremony is the Birdman Competition which is held in September ever year.
Each spring, the whole island awaited the arrival of the Manutara or Easter Island seagull, which nested in the motus (islets) near the Rano Kau volcano, especially in Motu Nui. Once it arrived, the tribes that would compete that year started a walk from Mataveri to Orongo, raised as a ceremonious city specially for this event, and the main representatives of each tribe settled in their homes, for as long as the ceremony lasted, which was around a month.
The chief of each tribe chose a hopu manu to represent them in the competition. Given the signal, the contenders would come down Rano Kau to the sea and swim 2 km to Motu Nui on a ‘pora’ or board of reeds that kept them afloat and let them take a few basic supplies. Once at Motu Nui, they settled into small caves waiting for the first manutara to lay an egg. The first one who managed to capture the egg would signal the crowd who waited at Orongo, indicating the chief that he was the winner. The race ended with this signal, though the winner had to place the egg in a band around his head and make his way back to present it to the chief, still intact. Days later, the egg was emptied and was hung in the new Tangata Manu or Birdman’s new house.
The winning tribe’s chief would shave his head and paint it red, in a way of preparing for his new role as the Birdman. Once this was done he began his procession to Mataveri to move into the house especially assigned to him in Rano Raraku, if his tribe belonged to the East Confederation, or in Anakena, if it belonged to the West.
During at least the first 6 months as the new Tangata Manu, he lived alone, with only the company of a servant or ivi-ahui which supplied him with food and other basic needs. The winning tribe would gain a bigger access to and control over the resources. Which any times translated to an abuse of power.
Most of the information and details we now have about this costume have been preserved thanks to exhaustive interviews done by Katherine Routledge in 1914 of people who had witnessed or participated in the last competitions, 50 years before.