The white bird in this picture, swimming between the ducks, was seen in Beijing, China, in januari 2017. It was cold: the water seen in the picture is liquid, but not far from this, the water was frozen. We also saw it standing on the ice.
It has an orange beak with what seems to be a small black spot at its end. It also has black as the top of its head. We did not find a similar bird when searching ducks, goose or even swans. What species is this?