[order] ANSERIFORMES | [family] Anatidae | [latin] Tadorna cana | [authority] Gmelin, 1789 | [UK] South African Shelduck | [FR] Tadorneaa tete grise | [DE] Graukopf-Kasarka | [ES] Tarro Sudafricano | [NL] Kaapse Casarca
The shelducks, genus Tadorna, are a group of large birds in the Tadorninae subfamily of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans. The namesake genus of the Tadorninae, Tadorna is very close to the Egyptian Goose and its extinct relatives from the Madagascar region, Alopochen. While the classical shelducks form a group that is obviously monophyletic, the interrelationships of these, the aberrant Common and especially Raja Shelducks, and the Egyptian Goose were found to be poorly resolved. Fossil bones from Dorkovo (Bulgaria) described as Balcanas pliocaenica may actually belong to this genus. They have even been proposed to be referable to the Common Shelduck, but their Early Pliocene age makes this rather unlikely.
Adult South African Shelduck have ruddy bodies and wings strikingly marked with black, white and green. The male has a grey head, and the female has a white face and black crown, nape and neck sides.
Listen to the sound of South African Shelduck
[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/South African Shelduck.mp3]
Copyright remark: Most sounds derived from xeno-canto
recorded by Derek Solomon
Africa : South. Southern Africa, from central Namibia and southern Botswana southwards.
During the breeding season this species inhabits small, permanent, shallow freshwater and brackish lakes, pools in river courses, rivers and exposed inland mud flats, in both upland and lowland areas of open country. In the non-breeding season the species prefers deep freshwater lakes, artificial reservoirs, salt pans, sewage works and shallow brackish pans. It may also be found away from water in natural grassland, Karoo veld, fynbos, ploughed land, stubble and fields of crops. This species requires large, deep freshwater lakes, reservoirs and dense swamps on which to undergo a post-breeding wing-moult.
It often nests on the slope of a hill at the end of old mammal burrows (typically those of Aardvark or Porcupine) or in other cavities that may be up to 2 km from water. Nests are lined with grass, down and feathers. The breeding starts in the dry season, begins June/July. Breeding is as solitary pairs, clutch size is 5-15 eggs which are incubated by the female for about a month. Young fledge after about 10 weeks. Newly hatched are protected by both parents.
During the breeding season in South Africa its diet consists entirely of vegetable matter, such as maize seeds and other ripe kernels and seedlings of grain crops (such as wheat, oats, barley and sorghum), potatoes, peanuts, sunflower seeds, rice and over-ripe figs. The species also takes the seeds, leaves and roots of grasses, reeds (e.g. Phragmites and Typha) and pondweed, as well as filamentous algae. During the non-breeding season the species is omnivorous, feeding on both animals (mainly crustaceans, brachiopods and insect larvae and pupae) and plants (submerged macrophytes). During the moulting period the diet of this species is predominantly made up of wheat seeds.
Video South African Shelduck
copyright: Josep del Hoyo
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 appears to be increasing, and hence the species does not approach the thresholds for Vulnerable 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.
Human recreation (e.g. watersports) poses a threat to this species through disturbance. In South Africa, the Aardvark is considered threatened so the species’s reliance on this mammal for nest sites is a concern. The species may also come under threat through range shifts or contractions as a result of climate change and West African populations have already come under threat by the desiccation of the Sahel zone. The species is susceptible to avian botulism, so may be threatened by future outbreaks of the disease. At the Klingnau Dam in northen Switzerland the species has been known to hybridise with Ruddy Shelduck Tadorna ferruginea from escaped captive populations, which could pose a threat to the integrity of both species.
This species is partially migratory over much of its range with substantial numbers of individuals undertaking seasonal movements related to the availability of water and moulting. Between November and December adult birds migrate short distances to congregate in flocks of around 400 to as many as 5,000 on large deep water lakes to undergo a flightless moulting period. The species then disperses in single pairs to breed between May and September, although large flocks of non-breeding pairs and single females may also occur at this time. Outside breeding and moulting seasons the species gathers in smaller flocks of several hundred birds.