Description
As members of the stiff-tailed duck group, Maccoas are often found wading in the water with their tail feathers cocked upwards. As diving ducks, their bodies are specialized for being agile underwater swimmers and thus have sacrificed the characteristics that allow them to move well on land. As a result, their legs are set further back on their bodies which makes them awkward when walking out of water.Male
The breeding male Maccoa stands out with its cobalt blue bill extending from a completely black head and throat. The breast and back are chestnut coloured while the underparts are often greyish-brown, the rump is dark brown, and the tail and feet are black. In flight, the male's off-white underwing feathers and white axillaries can be seen. Non-breeding males closely resemble the females, except for a few points: a darker crown and hints of chestnut colour on the back.Female
The female Maccoa is less colourful. It boasts a greyish-black bill with a light tip, and a light brown face with a dark crown and cheek stripe, and an off-white throat. The female also has a light brown breast, darker brown back, off-white underparts, black feet and black tail feathers.Juvenile
As with many birds, juvenile Maccoa ducks have similar plumage to adult females. However, their tail feathers are slimmer and notched, and their crowns are a darker brown.Taxonomy and systematics
The Oxyura genus is commonly referred to as stiff-tailed ducks. It is widely agreed that ''Oxyura'' and ''Nomonyx'' (a genus with a single species - the masked duck - '' Nomonyx dominicus'') are sister groups, and these results have been shown in both trait-based and genome-based phylogenies over the past 30 years. This genus has been separated into 2 groups: the Old World ducks consist of ''O. maccoa, O. leucocephala (white-headed duck),'' and '' O. australis'' (blue-billed duck), and the New World ducks are '' O. vittata'' (lake duck) and '' O. ferruginea'' (andean duck). The exact relationships between the different species of ''Oxyura'' are still undetermined. In 1995, a phylogenetic tree based solely on comparative traits suggested that ''O. maccoa'' and ''O. leucocephala'' were most closely related, while ''O. australis'' was put into a separate clade along with the New World species ''O. vittata'' and ''O. ferruginea.'' More recently, genetic analyses have found strong evidence that ''O. maccoa, O. australis, and O. leucocephala'' are more closely related to one another than they are to ''O. vittata'' and ''O. ferruginea''; however, the shape of their Old World clade and their evolutionary relationships relative to one another still remain unsolved. More recent studies have focused on comparing different genes across species, but these methods still yield conflicting results. Analyses examining mitochondrial DNA samples indicate that it is most likely ''O. leucocephala'' diverged first and that ''O. maccoa'' and ''O. australis'' share the most recent common ancestor. On the other hand, analyses comparingHabitat and distribution
Outside of the breeding season, Maccoa ducks tend to occupy inland waters - ranging from fresh toBehaviour
Vocalizations
When putting on their mating displays, males will often give out short whistles or will produce a prrrr'ing sound for 2 or 3 seconds. When feeling threatened, both males and females will emit low grunts.Diet
The Maccoa duck is an omnivore whose diet consists primarily of aquatic invertebrates and plants. The average dive lasts about 15 to 22 seconds, and it uses this time to fill its bill with dark debris sitting at the bottom of the lake or pond - a perfect habitat for many invertebrates. It then uses its mouth to sift through the material and keep the desired seeds, vegetation, and insects. When foraging underwater for vegetation, Maccoa ducks will eat a variety of plants - but seem to prefer species from the ''Reproduction
This species mates and lays its eggs typically between January and May, and spends this time in small, defended freshwater habitats with emerging vegetation, as mentioned above. The male Maccoa ducks are polygynous - meaning a single male will mate with multiple females - and they aggressively defend their breeding territory. These males do not provide any help with nest building or parental care. After mating, females remain in the male's territory and either build a new nest out of sedges, reeds, and down, or sometimes occupy the pre-existing nests of coots and grebes. Clutches are typically 5 or 6 eggs, but can reach up to 12 when females put their own eggs in another female's nest. In addition to this egg dumping, female Maccoas have also been observed abandoning their young both before and during incubation periods. The incubation period typically lasts from 25 to 27 days, but the fledging period is not well understood. Chicks are born with dark legs, feet, and bills, a white face, and are covered in grey-brown down. Interestingly, the breeding plumage of male Maccoa ducks can be influenced by their social rank. A study of captive Maccoa ducks in 1985 found that submissive males who were aggressively hassled by more dominant males had a lower social ranking, and these same males actually failed to acquire flashy and bright breeding plumage.Status and threats
Pollution
Unlike most other ducks who have a vegetarian diet, Maccoa ducks are omnivores who feed on plants as well as invertebrates. As a result, they are put in relatively high trophic positions compared to other ducks. For this reason, the species is more vulnerable to pollution because of the bioaccumulation and magnification of toxins in their diet. The most common sources of these dangerous pollutants are pesticides and herbicides carried in runoff from surrounding farms.Climate change
As the global climate continues to warm, it is likely that the wetlands of southern Africa which Maccoas depend on will start to dry up. Without such important breeding habitats, it can be expected that this species will soon show greater declines in their populations.Bycatch
A less prominent but still relevant threat to the Maccoa duck is accidental capture inReferences