While wood ducks have webbed feet and bills, they're very different from mallards, pintails and gadwalls. Woodies don't quack, they whistle. They nest in trees, not marsh grass, and favor acorns over sedge and grass. They don't fly, flock, decoy or migrate like other waterfowl, either. For these reasons, sportsmen trying to bag wood ducks are wise to follow specific tactics in locating and hunting these swift- flying "squealers."