The Old Duck Test

A close up of a Pacific Black Duck with an Australian Wood Duck in the backgroundThe old saying: If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck (known as the Duck Test), is an expression broadly used to infer that we should trust our judgement about what we are looking at. In the world of birds, there are few birds that look, swim and quack like a duck, so you are probably looking at a duck! But which one?

Within Australia, there are 26 members in this group of partially or fully web-footed birds. Of these, three are vagrants and two are introduced species. Although there is only one swan that is native to Australia, the world’s only black-coloured swan, the introduced Mute Swan is also found here. Three species of geese also occur in Australia, the introduced Canada Goose, found on Lord Howe Island, the Cape Barren Goose and the Magpie Goose. This latter species differs from all other members of this group by having only partially webbed toes, and because of this it has been placed in a family of its own. Of the remaining 21 species, the more common species are the Australian Wood Duck, the Pacific Black Duck, the Grey Teal, the Chestnut Teal and the Hardhead. This may change depending on the areas that you are visiting.

Diving Ducks

Species such as the Musk Duck, Blue-billed Duck, Hardhead, Green Pygmy-goose and Wandering Whistling-Duck, obtain some food by diving below the surface of the water. The Plumed Whistling-Duck, Australian Wood Duck, Australian Shelduck, Radjah Shelduck and vagrant Paradise Shelduck are seldom seen in the water, preferring to wade through the shallows or graze in grasslands. The Australian Shoveler, Northern Shoveler and Pink-eared Duck have specialist bills that they use to filter through the water for microscopic aquatic animals and plants. The remaining species follow the more traditional method of upending in the water and feeding on a variety of plants and animals from the bottom of their shallow wetland homes.

Pacific Black Duck perched on a tree root
A Pacific Black Duck

Perching Ducks

Perhaps the more extraordinary members of the large and widespread duck family, are the perching ducks. They are mostly quite different in appearance from one another, as well as from other species of duck. As the name suggests, the birds are generally arboreal in habits. Nesting in tree hollows is common, although certain species do nest on the ground. In keeping with this arboreal lifestyle the toenails are sharpened, certain species have enlarged eyes and/or elongated legs, and most have wide and rounded wings. The Australian Wood Duck, found in lightly timbered areas adjacent watercourses, is less arboreal than its relatives, preferring to grazing on ground vegetation. During the breeding season, however, suitable nest hollows are sought. If competition fro nesting sites is high, or their availability low, the birds may often travel up to a kilometre or more from water. The Australian Wood Duck is also called the Maned Duck or Maned Goose. This name is derived from the short black plumes on the rear of the male’s head. The name of goose refers to the upright stance of a bird as it walks. Other Australian members of this group are the Green Pygmy-goose and Cotton Pygmy-goose.

Australian Wood Duck feeding on pond weed in the water
Australian Wood Duck

Why Don’t Ducks Sink?

Ducks have a special gland called an oil gland. This gland is found on the rump of the bird, just above the tail. During the normal course of preening, an important process whereby the feathers are arranged, cleaned and generally maintained, the bird squeezes a fatty secretion (preen oil) from the gland using its bill. Both the head and bill are rubbed on the gland, and the oil is then applied evenly to all the feathers by rubbing and preening with the bill, head and feet. Ducks apply the oil to their feathers frequently, especially during and after bathing. The oil protects the feathers and down from becoming water-logged, by creating a film that is not penetrable by the water. The water simply beads into small droplets and runs off the oily surface of the plumage; hence the term “like water off a duck’s back”.

Can I feed bread to a duck?

The feeding of artificial or unnatural foods to birds is always discouraged, and many people would argue that feeding any wild birds may make them dependent on the provider. While some have stated that the birds would not get sufficient nutrition from bread, it is known that the increased nutrition obtained by Feral Pigeons that eat bread, has almost completely eliminated the occurrence of beri-beri. Dry bread may be harmful to birds as it swells up when it comes in contact with water, and thus may swell up inside the crop or stomach of the bird. Most ducks are, however, fed in the water. Here they are able to break up the larger pieces, so that they are more manageable, and the smaller pieces do not pose much of a problem. It would be wise, however, not to feed the birds on land, as the dry bread held in the stomach or crop, may swell up and be harmful once the birds drink. People have been feeding bread to ducks for many years and very few of them appear to be adversely affected by this activity; in fact, in species such as the Mallard, their numbers are higher in areas where the feeding of bread takes place. Pet suppliers provide a special feed for ducks that are kept in captivity, and this would be a more preferred food for any wild birds that are fed.

More Information and facts about ducks can be found in my book The Green Guide to Birds of Australia