Title: External features and molecular sexing of the anomalous Pintail, Anas acuta, found at Hyo-ko Waterfowl Park, Niigata Prefecture, Japan
Abstract: Phenotypic variation of the plumage including albinism and melanism is widely known among birds. On the other hand, morpho-chromatic variation of the plumage caused by hybridization has also been found in nature. Such an example is occasionally found in the Anatidae (Kuroda 1939), and possible hybrids of the Pintail Anas acuta with other species, e.g., Mallard (A. platyrhynchos), Teal (A. crecca), Baikal Teal (A. formosa), Gadwall (A. strepera), Wigeon (A. penelope), Shoveler (A. clypeata) and Pochard (Aythya ferina), were documented previously (Kuroda 1939). In fact, a presumptive hybrid between the Pintail and Bikal Teal was observed also in Hyo-ko Waterfowl Park, located in a suburb of Niigata City, Niigata Pref., Japan (Chiba, unpubl. data). During the course of bird-banding study in this Park, we incidentally found 2 unusual male Pintails, which were morphologically different from any known hybrids. The present study, therefore, was conducted to clarify the characters of these anomalous Pintails on the basis of macroscopic examination and molecular sexing.