In Illinois the basic daily limit is 6 ducks of any species. However, daily limit can consist of no more than the following: 4 mallards (of which no more than 2 can be hen mallards), 3 wood ducks, 3 scaup, 2 redheads, 2 canvasback, 2 black ducks, 1 pintail and 1 mottled duck. Possession limit for ducks is three times the daily limit by species and sex.
Can shoot five Mergansers a day in Illinois. Mergansers do not count toward your daily limit of ducks, but only 2 can be hooded mergansers. Merganser possession limit is no more than three times their daily limit, including max of 6 hooded mergansers. We don't eat them either.
Most ducks are easy to identify while on the wing, but some aren't. Best to know which ducks are severely limited like a hen mallard or a pintail and avoid shooting too many of them.