[2] They are in the National Museum of Natural History in Washington, D.C.[2] The bird was named in honor of Elliott Coues.

A male and a female are known, which resemble the immature appearance of the common gadwall except for the black bill with a higher number of filtering lamellae, black feet, and the much inferior size (which may be due to the birds not being fully grown).

[2] This means the birds were the size of a Cape teal or a garganey, with a total length of 40–45 cm.

The common gadwall is a known vagrant to the Tuamotu Islands (Kolbe wrote "Tahiti which is a misreading of Greenway)[7] and Hawaii for example, which are about the same distance from the species' breeding grounds, as is Teraina (which, moreover, lies in between these two groups).

[2][3][7] On the other hand, Streets' reports suggest that there was a population of these ducks of some size present, and thus they may have lived there for quite some time and indeed be worthy of recognition as a distinct taxon.