I think they do...seems during season I'd see a big pass of mallards heading north, back to the refuge during shooting light. Some days it was within woodie shooting hours, others it was as late as 9:00am. Over main river channels I'd see them flying much later than that, and not terribly high. Could've been reverse migration, but it seemed they were making a b-line for the refuge.
And right now if you're scouting WMAs for youth hunters it's surprising how much traffic there is.