Eastern Spot-billed Duck
Anas zonorhyncha

These ducks are the common summer duck in Japan and occur across much of East Asia with the population expanding northwards where it can hybridize with the Mallard. This species was split from the Indian Spot-billed Duck and both species look similar to the Pacific Black Duck, although it isn't entirely clear where the exact relationships in large Anas ducks lie, due to the complications in DNA testing from hybridisation (have a look here for a few more Mallard hybrids). As with other Anas ducks, they feed mainly by dabbling in the shallows and upending in deeper water, filtering out small prey and plant items with their bills. They are of a similar size to Mallards at 55–63 cm in length.
 

1: Ueno Park, Tokyo, 17/05/2012.