No matter how good you think you are at identifying ducks, it's easy to get confused, especially in the dim light of dawn or dusk.
"Even the most experienced waterfowl hunter, on any given day, might have to use multiple skills to identify specific ducks," said Mark Kakatsch, a waterfowl guide who gives seminars on how to identify ducks.
The three main areas of focus that Kakatsch uses for identifying ducks are the sound, the shape or silhouette, and the flight characteristics.
"On a sunny day, you can add color," he said.
Duck species can be divided into two categories: puddle ducks, which are found in shallow marshes, and divers, which favor deeper, open water. Puddle ducks include mallards, teal, pintails, wood ducks and shovelers; divers include canvasbacks, bluebills, red heads and ringnecks, sometimes called ring-bills.
"Most puddle ducks are more vocal than divers," said Kakatsch, of Oconomowoc.
Mallards are one of the most commonly hunted ducks in Wisconsin, but you're only allowed to take one hen mallard per day. So you not only have to identify the species but also the sex.
The mallard species is relatively easy to identify. It's a big duck with a long neck and a steady, deliberate, graceful wing-beat. Flocks often fly in "V" formation, circling a decoy spread before landing or moving on. But distinguishing a drake from a hen can be difficult, particularly early in the season.
After mating in the spring, drakes loose their bright "green-head" plumage and, for a while, they resemble hens. This is called eclipse drake plumage. During this time, Kakatsch relies on the telltale sounds.
"A hen mallard makes a distinctive quack," he said. "A drake makes a more low-pitched, drawn-out hum or purr."
If the ducks come in quietly, look at their bills.
"A drake's bill is olive, and a hen's is orange," he said.
Wood ducks make a unique, high-pitched, whiny, "kee-wee" sound.
"They have a shorter neck and a squared-off tail, unlike the mallard's rounded tail," Kakatsch said. "When it's light enough, you can see their crown, a tuft of feathers extending from the back of the head."
Wood ducks also have a more erratic flight pattern.
"They don't work the decoys by circling around," he said. "They either drop in on the first approach or they give you a look and keep on going."
Teal are the smallest puddle ducks.
"They're basically shaped like a mallard, but they're only about a third the size," Kakatsch said. "A green-winged teal makes a short whistling peep. A blue-winged teal makes a horse series of tick-tick-ticks."
Teal have quick wing-beats and fast, erratic flight.
"Teal like to fly in tight clusters, sometimes, just over the cattails," he said. "They do a lot of areal acrobatics, changing altitudes and directions."
The canvasback is the biggest of the diving ducks.
"It has a distinctive, angled, wedge-shaped bill," Kakatsch said. "They tend to fly in straight lines or `Vs,' but they're faster than mallards and you can usually see some white on the body."
Bluebills and redheads are close to the same size and shape, so color becomes the focus.
"A ring-bill is smaller than a redhead or bluebill, but the flight is similar," he said. "We get a lot of ring-bills and redheads that nest locally. Horicon Marsh is the largest redhead breeding ground east of the Mississippi River. Numerous ring-bills also nest in the marsh. Early in the season, they're around."
There are many duck identification books, pamphlets and videos available, and Kakatsch encourages hunters to study them or, better yet, take a duck identification course.
"Lack of identification skills could end up costing you money in fines for over-bagging of a specific species or by shooting a protected, non-huntable species," he said.
The books help, but Kakatsch said: "The best way to learn is to spend time in the marsh."