Gadwalls are most numerous in the Central Flyway, but not too common anywhere. They are often called "gray mallards" or "gray ducks." They are one of the earliest migrants, seldom facing cold weather. They are the only puddle ducks with a white speculum.
Small, compact flocks fly swiftly, usually in a direct line. Wingbeats are rapid. Drakes whistle and kack-kack; hens quack like a mallard, but softer.