Conservation and Management

Red List Category: Least Concern (59 BirdLife International (2021). Species factsheet: Tadorna cana. Downloaded from http://www.birdlife.org on 4/05/2021. Close ). The species has benefited from the construction of the large number of artificial waterbodies, especially dams, within its range, and anthropogenic changes to wetlands are usually to its advantage, as they typically result in a reduction of vegetation cover (91 Geldenhuys, J. N. (1976). Physiognomic characteristics of wetland vegetation in South African Shelduck habitat. South African Journal of Wildlife Research 6:75–78. Close , 10 Geldenhuys, J. N. (1981). Moults and moult localities of the South African Shelduck. Ostrich 52(3):129–134. Close ). Its ability to exploit fallen grain in crop fields has also benefited the species, especially due to the reliability and nutrient value of this food source, and its availability during the vulnerable period associated with molting (102 Siegfried, W. R. (1967). Trapping and ringing of Egyptian Geese and African Shelduck at Vogelvlei, Cape. Ostrich 38:173‒178. Close , 28 Geldenhuys, J. N. (1977). Feeding habits of South African Shelducks. South African Journal of Wildlife Research 7:5–9. Close ). This has resulted in an increase in the species’ abundance within its historical range and an expansion into previously unoccupied areas. Unlike several other waterfowl species, it has not benefited directly or indirectly from cattle feedlots in Gauteng Province (141 van Niekerk, J. H. (2010). Assemblages and movements of waterfowl at cattle feedlots across Gauteng, South Africa. Ostrich 81(1):31–37. Close ).

The concentration of a large proportion of the total population at relatively few sites during wing molt is potentially hazardous, but many of these sites are formally protected (10 Geldenhuys, J. N. (1981). Moults and moult localities of the South African Shelduck. Ostrich 52(3):129–134. Close ). The species is nevertheless sensitive during this period and requires ongoing protection from disturbance, such as from watersport enthusiasts (23 Dean, W. R. J. (1978). Molt seasons of some Anatidae in the Western Transval. Ostrich 49(2):76–84. Close ). Its reliance on Aardvark (Orycteropus afer) for nest sites is of concern as this mammal is considered threatened in South Africa (142 Geldenhuys, J. N. (1981). Breeding ecology of the South African Shelduck. South African Journal of Wildlife Research 10. Close , 3 Maclean, G. L., and G. Darroll (1986). Ducks of Sub-Saharan Africa. Acorn Books, Johannesburg, South Africa. Close ). Overall, however, its current conservation status appears healthy.

Habitat Loss and Degradation

The species could potentially be vulnerable to climate change through a radical, climatically induced, loss and shift in suitable habitat (143 Van Jaarsveld, A. S., S. L. Chown, B. F. N. Erasmus, M. Kshatriya, and K. J. Wessels (1999). Vulnerability and adaptation assessment of South African animal taxa to climate change. University of Pretoria, Pretoria. Close , 144 Erasmus, B. F. N., A. S. Van Jaarsveld, S. L. Chown, M. Kshatriya, and K. J. Wessels (2002). Vulnerability of South African animal taxa to climate change. Global Change Biology 8:679–693. Close ).

Shooting, Hunting, and Trapping

The South African Shelduck’s exploitation of agricultural fields renders it vulnerable to shooting, and intentional and accidental poisoning (102 Siegfried, W. R. (1967). Trapping and ringing of Egyptian Geese and African Shelduck at Vogelvlei, Cape. Ostrich 38:173‒178. Close , 28 Geldenhuys, J. N. (1977). Feeding habits of South African Shelducks. South African Journal of Wildlife Research 7:5–9. Close , 49 Tyler, S. J. (2020). Changing status of South African Shelduck (Cape Shelduck) Tadorna cana in Botswana. Babbler 66:4–10. Close ). This species is easily confused by farmers with the Egyptian Goose (Alopochen aegyptiaca), a notorious crop pest, and is sometimes persecuted as a result (28 Geldenhuys, J. N. (1977). Feeding habits of South African Shelducks. South African Journal of Wildlife Research 7:5–9. Close ). Apparently it is shot at Bloemfontein and Kimberley airports in South Africa during bird control operations to safeguard aircraft from collisions with flying birds (107 Kok, O. B., and S. M. Louw (2000). Avian and mammalian predators of orthoptera in semi-arid regions of South Africa. South African Journal of Wildlife Research 30:122–128. Close ).

The species’ meat is not very palatable, and this shelduck is difficult to hunt at wetland sites due to its relatively shy nature and the open nature of its preferred waterbodies (66 Horsbrugh, B. (1912). The Game-birds and Water-fowl of South Africa. Witherby and Co., London, UK. Close , 91 Geldenhuys, J. N. (1976). Physiognomic characteristics of wetland vegetation in South African Shelduck habitat. South African Journal of Wildlife Research 6:75–78. Close , 3 Maclean, G. L., and G. Darroll (1986). Ducks of Sub-Saharan Africa. Acorn Books, Johannesburg, South Africa. Close ). The South African Shelduck was available for legal recreational hunting under permit in the following South African provinces during 2021, with hunting season and individual daily bag limits in parentheses: North-West Province (1 January–31 March; 2), Western Cape (1 January–30 June; 5), Northern Cape (1 January–31 March; 5), and Eastern Cape (1 January–31 March; 2) (South African Wingshooters Association 2021). In Namibia it is listed under Schedule 4 of the Nature Conservation Ordinance 4 of 1975 and cannot be hunted for recreation (Namibia Biodiversity Database 2021). It is also not available for recreational hunting in Botswana.

Pesticides and Other Contaminants/Toxics

South African Shelduck could be threatened by water contamination, especially due to its extensive reliance on artificial wetlands, with particular relevance to potential large-scale hydraulic fracturing for shale gas, which typically produces large quantities of contaminated waste water, in the Karoo biome (145 Lee, A. T. K., C. Geary, D. R. Wright, and W. R. J. Dean (2019). Vulnerability of birds to contaminated water sources in the Karoo region of South Africa. Ostrich 90:397–406. Close ).

Collisions with Stationary/Moving Structures or Objects

In flight, the species is vulnerable to mortality via collisions with overhead power lines, and is also considered potentially vulnerable to electrocution on overhead electrical infrastructure, although it rarely (if ever?) perches above ground (146 Smallie, J. (2011). A power line risk assessment for selected South African birds of conservation concern. M.S. thesis, University of the Witwatersrand, Johannesburg, South Africa. Close , 147 Shaw, J. M. (2013). Power line collisions in the Karoo: conserving Ludwig’s Bustard. Ph.D. thesis, University of Cape Town, Cape Town, South Africa. Close ). Another potentially emerging threat could be in-flight collisions with blades of wind turbines, which are increasingly being installed in parts of the species’ range (148 Perold, V., S. Ralston-Paton, and P. Ryan (2020). On a collision course? The large diversity of birds killed by wind turbines in South Africa. Ostrich 91:228–239. Close ).

Information needed.