Many ducks have moved south, how far, I am not exactly sure. I have a small waterfowl guiding service I operate and in the early part of this week when the low temps were dipping pretty good, a good number of gadwalls, teal, wigeon, and woodducks left the northcentral part of the South Dakota.
The good news is that yesterday I spotted a couple, large flocks of Snow geese up by the NDakota/SDakota border. Coincidentally, a group of mine shot 30 northern mallards this morning in a cut cornfield with a butt load of decoys. Right now in northcentral SoDak, if there is a cut cornfield and water not too far from each other, you can really put the steel to them.
As far as any migration news, expect a fair number of birds to make it down your way within the next week or week in a half.
Good luck and remember, the only good spoonbill is a dead one!