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 ducks.:
“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.” 
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.” 
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:” 
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)).
A little update here:
A “surf duck” apparently is nothing but an albatross (Diomedea spp.), a bird that is well known to the Polynesians, even in the tropical parts of the region. 
 Teuira Henry: Ancient Tahiti. Bishop Museum Bulletins 48: 1-651. 1928  Kenneth P. Emory: Tuamotuan bird names. The Journal of the Polynesian Society 56(2): 188-196. 1947  Douglas L. Oliver: Ancient Tahitian Society. The University Press of Hawai’i, Honolulu 1974  Karen Stevenson; Steven Hooper: Tahitian fau – unveiling an enigma. Journal of the Polynesian Society 116(2): 181-212. 2007
We are more or less ‘housebound’ thanks to the Corona virus … so, we took a walk through the city.
It is now definitely spring because there are starlings singing from almost every tree.:
I usually don’t look at the Mallards because they are typical feral ducks, many of which don’t resemble wild ducks at all.:
Another sign for/of spring are singing Chaffinches, like with the starlings, almost every tree has its own singing Chaffinch right now, however, they are very difficult to photograph because they usually fly away as soon as they spot the camera.:
This is a Goldfinch, it has one of the most beautiful songs of all European birds.:
This little cutie was hopping about as close as only one meter away from us, so I could make at least two quite good pictures.:
“The most mysterious of all the Pacific waterfowl is Coues’ Gadwall, Anas strepera couesi, only two specimens of which have ever been found, on Washington Island, more than six hundred miles south of Hawaii. The two specimens, the male type and a female, collected in 1874, are now in the U.S. National Museum in Washington. In appearance these birds are simply Gadwalls reduced to about two-thirds normal size. The plumage too is rather dull and somewhat unfinished-looking. Washington Island is a marshy place only a few miles long, with a small brackich lake near the centre and a fringe of palms. Since he original pair of birds were discovered, several expeditions have stopped at the island, but no one has ever seen Coues’ Gadwall again. Speculation is perhaps unprofitable, but sometimes it is irresistible. I often like to wonder how these birds ever came to Washington Island. It is my guess, for what it is worth, that these two specimens represent the last of a very small inbred breeding population of true Gadwalls which by an accident of migration had become established on the island. I suspect that their size and coloration are due to environment and inbreeding rather than to any genetic change.“ 
This account summarizes quite well what’s known about this bird.
Then there are some strange accounts, or rather misinterpretations of accounts, let’s start with one that is rather less known, and speaks of the occurence of a form of gadwall on the Society Islands.:
“Forster met with a species of Gadwall on the Society Islands and identified it with A. strepera Linn. It is much more likely that is was C. couesi, for the range of that species doubtless extends beyond Washington Island, the only locality as yet known for it.” 
I read this original account by J. R. Forster, which is completely in Latin, and which merely is a enumeration of species, the duck is mentioned here just as “Anatem streperam“, that’s all, and this account almost for sure refers to the Pacific Black Duck (Anas superciliosa Gmelin), which occurs on the Society Islands, and which is not separately mentioned here … and in fact, Forster mentiones “Anas strepera” again in an enumeration of birds he describes from New Zealand, this also clearly refers to the Pacific Black Duck! 
Then there’s another account in a German book, which again is refering to an account in James C. Greenway’S “Extinct and vanishing birds of the world” from the 1960s.:
“Interessant ist eine weitere Bemerkung desselben Autors, wonach nach Angaben von Ripley ein auf den Tuamotu-Inseln gefundenes Entenkücken sich bei Erreichen der Geschlechtsreife als Schnatterente herausstellte.”
“Interesting is another comment of the same author [J. C. Greenway], based on which according to Ripley a duckling found on the Tuamotu islands, when reaching maturity, turned out to be a gadwall.” 
Okay … after purchasing J. C. Greenway’s book, which took me ages again, I can now proudly present you this abovementioned account by the ominous Ripley.:
“But, on the other hand, Dr. S. Dillon Ripley tells me that a duckling taken on the Tuamotu Islands was raised by Charles Nordhoff at Tahiti. When it reached maturity it turned out to be a gadwall.” 
That’s all, we actually deal with hearsay, an account of an account of someone who claimes to have caught a duckling on one of the Tuamotu Islands (these are actually the largest island group in the world consisting of no less than 76 atolls, just by the way ….) without naming the island in question.
However, given the geographic position of Washington Island/Teraina, a former occurence of this bird on the Tuamotu Archipelago makes much more sense than on the Society Islands.
But now let’s take a look on what these two persons, Dr. S. Dillon Ripley and Charles Nordhoff, have to tell; we start with Mr. Ripley …:
“It sometimes happens that migrating Ducks plummet down on to isolated islands in the Pacific. Mr. Charles Nordhoff told me once that a schooner captain inbound to Tahiti from Flint island, an isolated rock pinnacle three hundred miles or more north towards Hawaii from the Society Islands, brought him a duckling which he had picked up on the island. Mr. Nordhoff was able to raise the bird, and found that it was a Pintail, presumably from wild parents. If Pintails can fly so far south of Hawaii where they are in the habit of wintering, there seems no reason why Gadwalls should not be able to do the same thing.” 
… and go on with Mr. Nordhoff.:
“In his article in the Waterfowl number of the AVICULTURAL MAGAZINE, Dillon Ripley mentions a duckling I received some years ago from Flint Island, which when reared proved to be a fine male Pintail. I believe that a good many stray Ducks from the Northern Hemisphere land on the Pacific Islands, and occasionally, as Ripley suggests in the case of Coues’ Gadwall, give rise to a sedentary and eventually inbred race. I have reliable information that Shovelers in winter plumage have vistited both the Marquesas and the Tuamotu on several occasions, and that Pintail have been seen on Atiu in the Cook Group, south-west of Tahiti.” 
Well, well, so the Tuamotu Islands suddenly has changed into Flint Island, which in fact is not a part of the Tuamotu Archipelago but of Kiribati – and – the duckling that was supposed to turn out being a Gadwall was in fact a Pintail (Anas acuta L.), a completely different species of duck!
After all, we are left with probably more questions than answers.
 Johann Reinhold Forster; Hinrich Lichtenstein: Descriptiones animalium quae in itinere ad Maris Australis terras per annos 1772, 1773 et 1774 suscepto. Berolini: Ex Officina Academica 1844  Lionel K. Wiglesworth: Aves polynesiae: a catalogue of the birds of the Polynesian subregion (not including the Sandwich Islands). Berlin: R. Friedlaender & Sohn 1891 In: Abhandlungen und Berichte des Königl. Zoologischen und Anthropologisch-Etnographischen Museums zu Dresden Bd. 3: 1-84. 1890/91. herausgegeben von Hofrath Dr. A. B. Meyer, Director des Museums  Charles Nordhoff: Notes on the birds of Tahiti. The Avicultural Magazine ser. 5. 8(5): 119-120. 1943  Dillon Ripley: Pacific Waterfowl. The Avicultural Magazine ser. 5. 8(3): 67-70. 1943  James C. Greenway, Jr: Extinct and vanishing birds of the world. Dover Publications, 2nd Edition 1967  Dieter Luther: Die ausgestorbenen Vögel der Welt. Westarp Wissenschaften 1986
When James Richard Hill MacFarlane [unfortunately I could not find out who that actually was] stayed on Easter Island in February 1884, he made the following statement, which, however, appears to be very reliable after all.:
„The only birds I saw in the crater [Rano Kao] were three ruddy-coloured Geese, but I was unable to get anywhere near them.“ 
There were at least three geese on the island, straying around in the crater of the extinct Rano Kao volcano, but what can we make of this observation?
Well, given the date of this observation, 1884, these geese certainly were not an endemic species now lost, but given the recorded color they may also not have been feral geese, which are always either gray or white or mottled gray and white.
The authors of the most recent listing of native and introduced birds found on Rapa Nui, Manuel Marin and Pablo Caceres, think that what Mr. McFarlane saw may have been female Upland Geese (Chloephaga picta (Gmelin)), a species that inhabits southern South America and that either may have stranded on the island after they lost their route during a flight or, probably more likely, were imported to the island by humans. 
I will possibly post more interesting [I hope it is] stuff about this very, very isolated island in 2019.
 J. R. H. MacFarlane: Notes on birds in the western Pacific, made in H. M. S. ‚Constance‘, 1883-5. Ibis 5(5): 201-215. 1887  Manuel Marin; Pablo Caceres: Sobre las aves de Isla de Pascua. Boletín del Museo Nacional de Historia Natural, Chile 59: 75-95. 2010
While describing a new extinct bird, the Amsterdam Island Wigeon (Anas marecula) in 1996, the two authors Storrs L. Olson and Pierre Jouventin mentioned an account from the middle of the 18th century, and quoted another author, W. R. P. Bourne.:
„Of far greater interest, however, is the report of the explorer John Barrow, who was on St. Paul Island on 2 February 1793, where he mentioned the presence of „a small brown duck, not much larger than a thrush“ that was „the favorite food of the five sealers living on the island“ (quotes brom Bourne et al. 1983).“ 
To me, it seems, the two authors did not actually check the original source, John Barrow, here.
Well, but I did …! 😉
By the way; another well-known author of bird/extinction-related books, Julian P. Hume (in Extinct Birds; in the 2012 – or in the 2017 edition), even gives a completely wrong source.:
„John Barrow: Some Account of the Public Life, and a Selection from the Unpublished Writings, of the Earl of Macartney. Amsterdam London: T. Cadell and W. Davies. 1806“
I checked that source too! 😉
But back to the actual source, what does it really say?
„On the 1st of February we discovered the two islands of St. Paul and Amsterdam, and on the evening of the same day anchored on the eastern side of the latter, at the distance of about a mile from the shore. …“ 
The latter one is Amsterdam Island, right?
What follows are several descriptions of the island, of its geology, and some quite interesting philosophical reflections about the fact that some parts of the planet appear to be older/younger than others, and that islands apparently can just appear out of nothing or disappear into nothing, obviously without aid of an unearthly higher being (remember; Darwin’s ‚On the Origin of Species‘ first appeared 66 years after).
… oh, and a list of birds of course.:
„The number of birds was likewise astonishing, and the two causeways were strewed with teir eggs. During our short stay on shore we obtained the following birds: … Anas, A small brown Duck, not much larger than a thrush, and apparently not described by naturalists.“ 
The author still speaks about Amsterdam Island here, so this is the Amsterdam Island Duck (Anas marecula Olson & Jouventin)!
Its this little passage – „A small brown Duck, not much larger than a thrush“ – that apparently was copied again and again by several authors without checking the original source.
On page 155 resp. 156, the author reports about five seal hunters, that „all lived in a small miserable hut, as dirty and offensive as that of an Hottentot; and it was surrounded on every side by the dead carcasses of seals and sea-lions.“ 
„If the smoke and the fires of Amsterdam Island had excited our curiosity, the discovery of two or three human being running along the shore, as our ships approached it, on so miserable a spot, and so distant from any other land except the little neighboring island of St. Paul, caused a still greater degree of astonishment. …“ 
This passage clearly still refers to Amsterdam Island!
„The birds, they observed, had a strong fishy taste, to which, however, long habit had reconciled them: those that were the least so were the blue petrel and the little brown duck.“ 
There again, the small duck from Amsterdam Island!
The Amsterdam Island Wigeon clearly survived into the 18th century, since it is clearly that bird that is mentioned in the so often (incorrectly) cited quotes. There may a duck have existed on the Île Saint-Paul, however, up to now there is no proof for that assumption!
 John Barrow: A voyage to Cochinchina, in the years 1792 and 1793. To which is annexed an account of a journey made in the years 1801 and 1802, to the residence of the chief of the Booshuana nation. London: printed for T. Cadell and W. Davies 1806  W. R. P. Bourne; A. C. F. David; C. Jouanin: Probable Garganey on St. Paul and Amsterdam Islands, Indian Ocean. Wildfowl 34: 127-129. 1983  Storrs L. Olson; Pierre Jouventin: A new species of small flightless duck from Amsterdam Island, southern Indian Ocean (Anatidae: Anas). The Condor 98(1): 1-9. 1996