In ancient times, Tahitians believed that several of their Gods and other celestial beings would show themselves to the human eye in form of an animal, a so-called ata and Teuira Henry [see also here] lists some of them, among them also three kinds of duck.:

„Red-feathered duck (mo‘ora-‘ura), ata of ‘Orovehi‘ura (‘Oro in his manifestation of Red-feather-covered). 
Wild duck (mo‘ora-ōviri), ata of “sylvan elves.” 
Surf duck (toroa), ata of Hau, god of peace.“ [1][2]

The ‚Wild duck‘, mentioned here, is the Pacific Black Duck (Anas superciliosa J. F. Gmelin) which is the only duck species known from French Polynesia at all, so what are the other two ‚ducks‘?

„The most showy headdress worn officially by the king and princes and high chiefs was the taumi, a superb helmet made of clusters of crimson feathers of the moora ‘ura (red-feathered duck), set upon a light framework and covering the head like a bird, with a glossy terminal behind of outspreading red, black, and white feathers tastily mixed together.“ [1][2]

A taumi, however, actually is a gorget decorated with feathers, a feathered helmet was called fau.:

„Henry gives a description of a headdress which has some characteristics of a fau, but which seems to be a mixture of remembered types, further confused by the use of the name taumi, which we know was a gorget:“ [3]

The fau was also decorated with several of the elongated tail feathers of tropicbirds (as you can see in the depiction, in which they are from the White-tailed Tropicbird (Phaethon lepturus ssp. dorotheae Daudin)).

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References:

[1] Teuira Henry: Ancient Tahiti. Bishop Museum Bulletins 48: 1-651. 1928 
[2] Douglas L. Oliver: Ancient Tahitian Society. The University Press of Hawai’i, Honolulu 1974
[3] Karen Stevenson; Steven Hooper: Tahitian fau – unveiling an enigma. Journal of the Polynesian Society 116(2): 181-212. 2007

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edited: 27.07.2020