When you resemble one of the most common waterfowl species in North America, sometimes it's hard to stand out. Noting subtle differences and a careful eye, one can fairly easily pick a Gadwall out of a lineup of Mallards, however.
Gadwall male. Photo by Mike Budd/USFWS
Gadwall have a steep forehead and a thinner bill. Females very much resemble female Mallards, though Gadwall have a more squared off head. Males are easier to tell apart, and the male Gadwall sports an attractive gray overall, with touches of brown and rust on his head and back. His black rump patch can give him away more easily. Surprisingly, Gadwall form pairs as early as late fall, so in Wisconsin when you see the birds migrating through, they're often paired up, which makes identification a bit easier. Once you see the male Gadwall, you can then study the female for differences with a Mallard.
Male and female Gadwalls. Photo by Andy Reago & Chrissy McClarren
Gadwall do breed in Wisconsin, mostly in the prairie pothole regions of southeastern Wisconsin at sites like Goose Pond and Grassy Lake, and in northwestern Wisconsin near water in the barrens and prairie regions, at sites like Crex Meadows. Gadwall will often nest on islands, which protects their nest from potential predators. Research has found that species richness of the nesting site correlated with nesting success in Gadwall–as species fill various niches, the layering from top to bottom becomes more complex, and it's thought that this layering better hides the nest.
Gadwall nest. Photo by Krista Lundgren/USFWS
You can find Gadwall, usually migrating through, dabbling in Faville Grove wetlands as they thaw out. And if you see a group of mallards, make sure to be in the lookout for an oddball pair.
Written by Drew Harry, Faville Grove Sanctuary land steward
