Cape shelduck

Tadorna cana

Kaapse casarca (Grijskop casarca) / Graukopfkasarka / Casarca du Cap

The Cape shelduck is a species in the subfamily of Tadorninae, a group of large goose-like birds which are part of the bird family Anatidae, which also includes the swans, geese and ducks. The duck breeds in southern Africa, mainly in Namibia and South Africa. In the southern winter, many birds move north-east from the breeding range to favoured moulting grounds, where sizable concentrations occur. This species is mainly associated with lakes and rivers in fairly open country, breeding in disused mammal holes, usually those of the Aardvark (Orycteropus afer).

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 (IUCN, 2012).

Human recreation (e.g. watersports) poses a threat to this species through disturbance (Kear 2005a). In South Africa, the Aardvark is considered threatened so the species's reliance on this mammal for nest sites is a concern (del Hoyo et al. 1992, Kear 2005a). The species may also come under threat through range shifts or contractions as a result of climate change (van Jaarsveld et al. 2005) and West African populations have already come under threat by the desiccation of the Sahel zone (Scott and Rose 1996). The species is susceptible to avian botulism, so may be threatened by future outbreaks of the disease (Blaker 1967, van Heerden 1974). 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 (Owen et al. 2006). The species is hunted mainly for sport (Littleet al. 1995, Hockey et al. 2005, Kear 2005a), but there is no evidence that this currently poses a threat.

Captive breeding management

By Dan Cowell

The Cape shelduck, or South African Shelduck, lives along riverbanks, ponds and shallow lakes in South Africa.
Sometimes confused with the Ruddy shelduck, drakes have a gray head and neck with buff breast. The rest of the body is chestnut red, similar to the Ruddy.
Hens are close in appearance to the drake, but have a white face surrounded by a darker brown head.
There are many orinthologists that believe the Cape shelduck is in fact a subspecies of the Ruddy, due in large part to their similar appearance and habits. Their care in captivity is nearly identical to the Ruddy. They are aggressive towards other species and will need to be housed apart from smaller ducks.
Their breeding season is from May to June, in the wild, they use holes and burrows made by other animals, in captivity, use a half-buried, as in other shelducks. They lay 7 to 15 eggs which hatch after 30 days. Ringsize: 13mm

Above: adult male Cape shelduck

Above: adult female Cape shelduck

Above: an adult pair of Cape shelducks, female in front

Above: male Cape shelduck moulting its flight feathers

Above: close-up of an adult male Cape shelduck