The freckled duck (Stictonetta naevosa) is a waterfowl species endemic to Australia. The freckled duck has also been referred to as the monkey duck or the oatmeal duck. These birds are usually present in mainland Australia, but disperse to coastal and subcostal wetlands in the dry period. During such times it is common for the freckled duck population to congregate in flocks in the same area, giving the impression that they are more common than they really are.
The freckled duck population is at risk of further reduction from habitat destruction, droughts and game hunting. Often habitat destruction and drought can lead to an increase in hunting, as the freckled duck is forced to disperse into more coastal ranges where they may not be recognised as a protected species.
In the past few decades, several institutions have established breeding programs to aid in supplementation of the freckled duck population. Such establishments included, but are not restricted to the Hunter Wetlands Australia, Slimbridge Wetlands, Melbourne Zoo, Bronx Zoo, Adelaide Zoo, Healesville Sanctuary and Tidbinbilla Nature Reserve. The success of these institutes has been variable, with some failing to establish self-maintaining colonies.
The freckled duck has a distinctive appearance. It is characterised, in adults, by dark grey to black plumage covered with small white flecks, which gives the duck the ‘freckled’ look. The feet, legs and bill of both sexes is of a slate grey colour. Hatchlings and juveniles are distinguished by a uniform light grey plumage, which they lose around their 32nd week when they undergo a full body moult to assume the adult plumage.
The adult freckled displays a few sexual dimorphisms, the first being size. On average, males are the larger sex, with average weight between 700 – 1200g. Females have an only slightly lower range between 600 – 1200g. Both sexes have a length of 50 – 60 cm. During the breeding season particularly, the males are characterised by the base of their culmen, which takes on various shades of red. Those in prime reproductive condition take on a deep red colouring, while other males may only develop lighter shades of red, or in some instances, no colouring at all. Deep red colouring of the culmen is also associated with dominance, and those with the deepest red are those likely to breed with the females of the group.
The freckled duck is a polygamous species that undertakes short term, seasonal monogamous pairings in the wild. In this short term pairing, the male defends the receptive female during the pre-egg laying stage of the breeding season. During this time, the male also helps construct and defend the nest site—but leaves before the female lays her clutch, and plays no further role in rearing or defending his offspring.
The freckled duck has few pre or post copulatory behaviours. Copulation occurs in the water with the male approaching a receptive female who, adopts a semi-submerged orientation, with her head stretched outwards and tail raised. The male then mounts the female and clutches the feathers on the lower neck of the female during copulation. After dismounting, both sexes display bathing and preening behaviours.
The breeding season of the freckled duck is basically regular, with a generic breeding season between September and December. However, it retains the ability to breed out of season. Breeding out of season highly correlates with periods of heavy rainfall and flooding.
Both male and female freckled ducks reach sexual maturity at around 12 months of ages when the first breeding occurrence can commence. The freckled duck has been known to continue breeding annually throughout their life, with records suggesting successful breeding in birds in excess to 10 years of age.
The freckled duck has a standard incubation period of between 26–28 days, though some sources have recorded incubation periods of up to 35 days. The female is solely responsible for egg incubation and only leaves the eggs for short periods to feed.
The average clutch is seven eggs, but can range between four and 14 eggs. Clutches of up to 14 eggs can occur naturally, though this occurrence mainly appears to be the result of females ‘dumping’ additional eggs into another female’s nest. This occurrence is common within freckled duck populations as it enables the offending females to pass on their genetic material while not expending energy to raise their hatchlings.
The eggs of the freckled duck are glossy, smooth and almost perfectly oval in shape. They are white in colour, ranging from shades of cream to ivory. The freckled duck egg is unique, having an exceptionally thick but soft shell unlike that of any other species. Egg measurements usually fall between 60-65mm by 45-48mm and weigh an average of 66g.
Freckled duck hatchlings are precocial, meaning they hatch fully functional and able to feed themselves. Despite this, they still need their mother for the best chance of survival.