At Onuma a large flock of Mallard joins the Whooper Swan on a small ice free patch of the lake every year. Other species join too: there are usually a few Smew, Goosander and Goldeneye and for several winters a small group of Pintail. Bean and White-fronted Goose sometimes put in an appearance too.
3 years ago I noticed small numbers of Falcated Duck on the edge of the group, generally just out of camera range. And 2 years ago there were small numbers of Baikal Teal, again out of range.
Last year both species did come close enough for some pictures (but sadly not any Baikal drakes) So far this winter neither species has appeared……………….
Both the first 2 species are scarce but not especially rare in this part of the world. The female Ring-necked Duck came for 2 consecutive winters. Again, well out of camera range but a nice bird to see and a bona fide rarity.