Meet the Falcated Duck: The Gadwall Duck’s Closest Relative

The Gadwall is a medium-sized dabbling duck that is most often found in freshwater wetlands such as marshes, lakes, and quiet ponds. It is similar in size to a wigeon and is known for its strong flying ability and tendency to move in tight, coordinated flocks.

Although it is widespread across the Northern Hemisphere, it is often overlooked because of its relatively plain appearance compared to more brightly coloured ducks.

Male Gadwalls have finely patterned grey plumage with subtle chestnut and black accents, while females are light brown and well camouflaged but more intricately marked than many other female ducks.

One of the most useful identification features in both sexes is the distinct white wing patch, which is visible in flight and at rest.

Despite its understated look, the Gadwall is a well-adapted and highly successful wetland species.

Gadwall’s Closest Relatives

The Gadwall was first formally described in 1758, but modern DNA studies have helped scientists better understand where it fits among other ducks. These studies show that the Gadwall is most closely related to the Falcated Duck, and together they are closely linked to the wigeons.

At first glance, the falcated duck and gadwall may not look alike, especially the males.

The male has finely patterned grey body plumage with a delicate, textured appearance, but its most striking feature is the long, curved, sickle-shaped tertial feathers that extend elegantly from the back. The head is dark green with a glossy sheen, contrasted by a clear white throat and a narrow dark green collar. The crown has a bronzed tone, adding to its rich, multi-layered colouring. The rear of the body shows a mix of yellow, black, and white markings, creating a complex pattern around the vent area.

In flight, both sexes show pale grey underwings and a dark speculum bordered with white on the inner edge.

The female is much plainer, being dark brown overall with a shape and plumage similar to a female wigeon, but it can be identified by its relatively long grey bill.

The Gadwall, in comparison, is much more subtle in colour and pattern. While the male Falcated Duck stands out immediately with its bold head colours, glossy green tones, and long, flowing sickle-shaped tertial feathers, the Gadwall has a far more restrained and finely detailed appearance.

The breeding male Gadwall is mainly grey with delicate patterning rather than strong contrasts, and instead of ornamental feathers, it shows clean lines and a neat, structured look.

 Its most noticeable feature is the white wing patch, which is clear in flight but far less dramatic than the Falcated Duck’s elaborate plumage.

The female comparison is even closer in tone: both are brown and well camouflaged, but the Gadwall female is slightly more finely marked and can be told apart by its cleaner wing pattern and distinct white speculum.

 Overall, where the Falcated Duck is decorative and eye-catching, the Gadwall is understated, balanced, and designed more for blending into wetland environments than for display.

The Genetic Link

Modern research comparing DNA has revealed that the Gadwall and the Falcated Duck are sister species, meaning they share a very recent common ancestor. In fact, their genetic lines are so closely connected that scientists have found signs of past interbreeding between them.

Some Gadwalls even carry genetic material that likely came from Falcated Ducks thousands of years ago. This suggests that these two species not only split from a common ancestor relatively recently (in evolutionary terms), but may have interacted again later where their ranges overlapped.

Wigeons are the next closest relatives. While slightly more distant, they still belong to the same tight evolutionary group, which is why all three are now classified together.

Wigeons are medium-sized dabbling ducks known for their rounded heads, short bills, and distinctive whistling calls. Like Gadwalls, they are commonly found in wetlands such as lakes, marshes, and coastal areas.

Wigeons tend to spend a lot of time feeding on land, grazing on grasses, a behavior that’s less common in many other ducks and gives them a slightly different lifestyle compared to the more water-focused Gadwall.

How many wigeons can you name or identify? Check out the most common types of wigeons in this post: 6 Types of Wigeons You Should Know