THE GREY DUCKS.
THE group of Grey Ducks comprises two species of Indian Ducks which are usually united to the True Ducks; the Grey Duck being associated with the Wild Duck, and the Andaman Duck with the Common Teal.
The Grey Ducks differ from the True Ducks in so many important respects that I am obliged to regard them as a very distinct group. They have given up their migratory habits and have become localised. As a consequence, they require to fly less, and the wing is therefore more blunt than in the True Ducks, as indicated by the greater length of the outer secondaries, the tips of which, in the closed wing, reach to the tips of the longest primary coverts. The lengthening of the outer secondaries in the Grey Ducks causes the speculum to be very large. The primaries, instead of presenting the peculiar pattern observable in the primaries of the True Ducks, are blackish throughout. The sexes are quite alike, and the male is clothed in the sombre plumage of the female, although both sexes exhibit the brilliant speculum so characteristic of both sexes of many species of True Ducks. Inasmuch as the drake resembles the duck, there is no necessity for a post-nuptial moult, and there is no evidence to show that the drakes of the Grey Ducks have any but the ordinary autumnal moult.
The plumage of the Grey Ducks is more or less spotted. The bill resembles that of the domestic Duck, and is of equal width throughout its length.
In this group should be placed the Chinese Grey Duck (P. zonorhyncha), which may probably be found in the eastern parts of the Shan States.* It resembles the Indian Grey Duck, but may be distinguished by the following characters. The bill is black, with the tip of the upper mandible alone yellow. The speculum is brilliant metallic blue, and there is a double band of black and white below it. Above the speculum, however, instead of a similar double band, as in the Indian Grey Duck, there is but a single band, of a black colour. Instead of the outer webs of the two long secondaries next the speculum being entirely white, these webs exhibit hardly any white. The Chinese Grey Duck has a wide range, extending from Japan down to China. It is a resident species, but its southern limits are not definitely known. There is no other Grey Duck likely to occur within the limits of the Indian Empire.*
* As this is passing through the press I see in the "Asian" (January 10th, 1899), that a correspondent states that he has shot Spotbill Ducks, which he terms zonorhyncha, at Kengtung, in the Shan States.
* There is no genus in which the Grey Ducks can be placed, and I therefore propose the name Polionetta for them, with Polionetta poecilorhyncha as the type of the genus.