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