The Tahitian Sandpiper, Prosobonia leucoptera, is an extinct member of the large wader family Scolopacidae that was endemic to Tahiti in French Polynesia.
It was discovered in 1773 during Captain Cook's second voyage where it seems that a single specimen was collected, but became extinct in the nineteenth century. Only one museum specimen is known to exist. The bird's name in the Tahitian language was transcribed as torom?.
Description
Based on Zusi & Jehl (1970): A small (some 18 sm long), plain-colored sandpiper, brown below, darker above, with a white wing patch. Top and sides of head and neck to wings and back sooty brown, darker on back and wings. A small white patch behind and above the eye. Chin buffish white. Lores, rump and underside rusty. Wing coverts with some rusty edging. Remiges with paler inner surfaces. Underside of wing dusky brown with paler edges to coverts. A crescent-shaped white patch formed by tertiary coverts; smaller on the underside of the wing. Ten primaries, twelve rectrices. Central tail feathers sooty brown with rusty tips; outer ones rusty with sooty brown barring.
Bill blackish, lower mandible slightly paler, pointed, thin and short, rather like in an insectivorous passerine than a wader. Legs greenish-hued pale straw color. Toes unwebbed. A slim pale rusty ring around the eye. The iris was very dark brown.
The Tahitian Sandpiper is believed to have occurred near small streams.
Two (probably) specimens taken on Moorea by William Anderson between September 30 and October 11, 1777, formed the basis for the description of the White-winged Sandpiper. The 3 specimens which were mentioned by John Latham in 1787 all differed from one another, but the single remaining one, RMNH 87556, cannot be positively identified with any of them and how it came into the possession of the museum cannot be retraced with complete certainty, but it probably was acquired in 1819 with other Forster specimens (Stresemann, 1950). In addition, there exists a painting by Georg Forster drawn from the original specimen (see below) and a beautiful lithograph reconstruction by John Gerrard Keulemans.
At any rate, the specimen agrees better with the Tahiti bird in Forster's painting, the Moorea bird - of which another painting, by William Ellis and a plate by J. Webber, supposed to depict the other specimen, constitutes all remaining evidence - differing in the color of wings and head. Whether these two forms were species, subspecies or simply variants due to age or sex cannot be determined with certainty, but for the time being, they are more often being treated as different species than not.
Bones of a related form have been found on Mangaia in the Cook Islands. It is not likely that they will be studied anytime soon: a scientific description would require either successful extraction and analysis of DNA from both the bones and the Leiden specimen (which would risk being damaged during extraction of the tissue sample), or the collection of a sufficient amount of material from Tahiti and/or Moorea to determine the Mangaia bird's affiliation by analysis of the osteology. Both possibilities seem very remote.
