[order] ANSERIFORMES | [family] Anatidae | [latin] Anas superciliosa | [authority] Gmelin, 1789 | [UK] Pacific Black Duck | [FR] Canard a sourcils | [DE] Augenbrauen-Ente | [ES] anade Cejudo | [NL] Wenkbrauweend
Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers in a number of subgenera. Some authorities prefer to elevate the subgenera to genus rank. Indeed, as the moa-nalos are very close to this clade and may have evolved later than some of these lineages, it is rather the absence of a thorough review than lack of necessity that this genus is rather over-lumped. The phylogeny of this genus is one of the most confounded ones of all living birds. Research is hampered by the fact the radiation of the two major groups of Anas ? the teals and mallard groups ? took place in a very short time and fairly recently, roughly in the mid-late Pleistocene. Furthermore, hybridization may have long played a major role in Anas evolution, with within-subgenus hybrids regularly and between-subgenus hybrids not infrequently being fully fertile. The relationships between species are much obscured by this fact, and mtDNA sequence data is of dubious value in resolving their relationships; on the other hand, nuclear DNA sequences evolve too slowly to resolve the phylogeny of the subgenus Anas for example. Some major clades can be discerned. For example, that the traditional subgenus Anas, the mallard group, forms a monophyletic (in the loose sense, i.e. non-holophyletic) group has never been seriously questioned by modern science and is as good as confirmed (but see below). On the other hand, the phylogeny of the teals is very confusing. For these reasons, the dabbling duck lineages more distantly related to mallard group (which includes the type species of Anas) than the wigeons should arguably be separated in their own genera. These would include the Baikal Teal, the Garganey, the spotted black-capped Punanetta group, and the shovelers and other blue-winged species. Whether the wigeons, which are very distinct in morphology and behavior, but much less so in mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequences, should also be considered a distinct genus Mareca (including the Gadwall and Falcated Duck) is essentially the one remaining point of dispute as regards the question which taxa should remain in this genus and which ones should not.
The Black Duck is a dark-brown bird with a pale face and throat. It has a distinctive black eye-stripe that stretches from the top of the bill through the eye. The male and female have a similar appearance. In flight, the Black Duck is a dark bird with swift wing beats and a slender neck. The upperwing has no white but does have a green glossy colour patch on it. The underwing is white. On the water, the Black Duck is a medium-sized duck with a slender head and neck which is carried erect.
Listen to the sound of Pacific Black Duck
[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Pacific Black Duck.mp3]
Copyright remark: Most sounds derived from xeno-canto
recorded by Daniel Lane
Australasia : widespread
The Black Duck occurs across a wide range of habitats from deep, permanent, reed-dominated freshwater wetlands to rivers, creeks and brackish or saline wetlands.
Mating in Pacific Black Ducks coincides with availability of sufficient food and water, and often with the onset of heavy rains or when waterways are at their peaks. Courtship is accompanied by ritualised displays including preening, bobbing and wing-flapping. This behaviour is often initiated by the female, and, other than copulation, the male helps little in the breeding process. Often, two broods will be raised in a year. The number of offspring produced may seem quite high, but only 20% of these will survive past two years of age. Nests range from scrapes in the ground to well-woven cups in grass or reeds also holes in trees stumps, in deserted nests of other water birds or flat surfaces in staghorns and large low ferns. The female plucks soft small feathers from her breast to line the nest area and also to cover the 8-10 eggs when she leaves to go off and feed accompanied by the male. Eggs are oval with a smooth glossy white shell and the female incubates them for 26-32 days. Ducklings are semi- precocial ? hatched with eyes open, covered with down, capable of walking and swimming soon after hatching but stay with the parents near the nest. The young fledge after about 2 months, sexual maturity is reached after 1 year; a study showed 20% of the newly born reaches the fledging stage.
The Pacific Black Duck is mainly vegetarian, feeding on seeds of aquatic plants. This diet is supplemented with small crustaceans, molluscs and aquatic insects. Food is obtained by ‘dabbling’, where the bird plunges its head and neck underwater and upends, raising its rear end vertically out of the water. Occasionally, food is sought on land in damp grassy areas
copyright: Stephen Wallace
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The introduced Mallard presents a particular danger to the Pacific Black Duck as they have similar food and habitat needs and so complete for survival. When these two species interbreed the feral Mallard strain is dominant and in successive generations the characteristics of our native Pacific Black can be lost. In addition the Mallard imparts unfavourable traits to these hybrids such as that they are sedentary birds and not able to survive the erratic (and ever more so) climate of Australia and so do not adapt as pure native duck species, which are nomadic especially in times of drought.
Found throughout Australia, except inland deserts, mainly where fresh water is present but sometimes salt water, they are randomly nomadic following floods but will be rather more sedentary on permanent waters especially on eastern and northern coastal areas and part of this can be attributed to human feeding. In southeastern Australia seasonal shifts in populations, north over winter and south in spring and summer. Across northern Australia the birds stay on coastal waters during winter-spring dry season and then disperse inland with the summer monsoons