The duck family can be divided into three groups: the surface-feeding or ‘dabbling’ ducks, diving ducks, like the Tufted, which occur mainly in freshwater habitats, and sea ducks, such as eiders and scoters, all of which dive for their food. The Gadwall belongs in the first category.

Some of the gaudy drakes in the wildfowl world are a bit too ‘Art Deco’ for my taste, but the male Gadwall combines its sleek shape with a sophisticated blend of browns and greys which must still be attractive to the dowdier females of the species as well as providing an element of camouflage.

Gadwalls have a wide range across North America and Eurasia but are commonest in the warm temperate zone. In north-western Europe the recent extension of their breeding range to Iceland in the second half of the last century may have been one of the first avian indicators of global warming, which no doubt went unrecognised at the time. In Iberia it is resident where clean, shallow lakes or coastal marismas occur. Isolated breeding pairs may take advantage of undisturbed small ponds and slow-moving rivers and streams. In winter the resident birds are outnumbered by immigrants from further north.

The Gadwall

The Gadwall was considered uncommon in Iberia as recently as the 19th Century. As in most of Europe, numbers increased throughout the 20th but now seemed to have stabilised at around two to three thousand pairs, most of which are in Spain. The creation of large reservoirs and wetland reserves may have been partly responsible for this success, as well as a reduction in hunting pressures. In southern Portugal the best place to see it at close quarters is the freshwater lagoon at Quinta do Lago.

Gadwalls often associate with other ducks in winter, including the similarly-sized common Mallard. Although not visible on swimming birds, Gadwalls of any sex or age are easily identified in flight by the square white patch on the rear of the inner wing.

Although a member of the ‘surface-feeding’ fraternity, Gadwalls obtain much of their plant food from below the surface, swimming with their heads under water but only rarely ‘up-ending’. Hence their preference for shallow lakes.