Distribution

The South African Shelduck is endemic to southern Africa (43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close , Second Southern African Bird Atlas Project). The species breeds virtually throughout its usual range, which encompasses the semi-arid southwestern region (< 600 mm/annum) of southern Africa, centered on the Karoo (dwarf shrubland) biome, and spans both the summer- and winter-rainfall regions of southern Africa (44 Geldenhuys, J. N. (1981). Effect of temperature and rainfall on the distribution of the South African Shelduck Tadorna cana. South African Journal of Zoology 16:167–171. Close , 43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close ), although it is apparently largely a non-breeding summer visitor to the latter region (45 Winterbottom, J. M. (1968). A Check List of the Land and Fresh Water Birds of the Western Cape Province. Annals of the South African Museum 53:1–276. Close ). Its overall distribution is similar to that of the Cape Teal (Anas capensis), and both species show a preference for drier regions with brackish waters. The mean temperature of the coldest month, July (10˚C), when the species breeds, is correlated with its distributional limits. South African Shelduck largely avoids the true desert of the Namib, but is found in more mesic regions around the periphery of its core range in the fynbos/macchia (mesic shrubland), grassland, and Kalahari (savanna) biomes. The primary determinants of its essentially temperate distributional limits may be a direct intolerance of high temperatures when breeding, perhaps at least partially explaining the species’ choice of nest site, and an avoidance of higher rainfall areas due to a similar intolerance of the densely vegetated wetlands typical of mesic regions (44 Geldenhuys, J. N. (1981). Effect of temperature and rainfall on the distribution of the South African Shelduck Tadorna cana. South African Journal of Zoology 16:167–171. Close ).

It occurs widely in South Africa, especially in the west. In Namibia, it is commonest in central regions but occurs as far north as the Angolan border. There is a recent (May 2019) bird atlas record from the Zambezi Region, previously known as the Caprivi Strip (pentad 1750_2315). In Botswana, it is common only in the extreme southeast, but there are numerous records from virtually throughout the country including from the extensive wetlands in the far north (46 Milewski, A. V. (1975). New distributional data 6: South African Shelduck Tadorna cana. Ostrich 46:167. Close , 47 Dowsett, R. J., C. A. Brewster, and C. Hines (2011). Some bird distributional limits in the Upper Zambezi Valley. Bulletin of the African Bird Club 18(1):17–30. Close , 48 Hancock, P., and I. Weiersbye (2016). Birds of Botswana. Princeton University Press, Princeton, NJ and Oxford, UK. Close , 49 Tyler, S. J. (2020). Changing status of South African Shelduck (Cape Shelduck) Tadorna cana in Botswana. Babbler 66:4–10. Close ). In Lesotho, the species is uncommon and largely restricted to the lowlands, typically avoiding the country’s high-lying massif (50 Osborne, P. E., and B. J. Tigar (1990). The status and distribution of birds in Lesotho. Unpublished manuscript, Nature Conservation Bureau, Newbury. 336 pp. Close ), although one (Letšeng-la-Letsie) of the two most regular sites for the species is in the southern highlands at 2,400 m (51 Ambrose, D. (2020). Lesotho Annotated Bibliography, Section 167A, Birds – Annotated Bird Checklist. House 9 Publications and Mohokane Trust, Roma, Lesotho. Close ). It is largely a non-breeding visitor to Lesotho and the only breeding record is from Morija in the western lowlands during June‒July 2016. There are two records from Zimbabwe: the first near Bulawayo in August 1973 (52 Webb, D. (1973). Letters to the the editor. Honeyguide 76:42. Close ), and the second at Lake Manyame, near Harare, in November 2009 (53 Chiweshe, N. (2012). A second record of the South African Shelduck in Zimbabwe. Honeyguide 58(1):66. Close ), although the latter perhaps requires confirmation (54 Riddell, I. C. (2015). Comments on birds of the 2007–11 Manyame Lakes survey. Honeyguide 61(1):45–46. Close ). A record from central Eswatini in March 2011 (pentad 2630_3115) appears to be the only one in the country (55 Parker, V. (1994). Swaziland Bird Atlas 1985-1991. Websters, Mbabane, Swaziland. Close , 43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close ), although the species has been recorded several times further south in the Jozini Dam area, a waterbody straddling the Eswatini/South Africa border. The species has not been recorded in Mozambique (56 Dowsett, R. J. (1993). Afrotropical avifaunas: annotated country checklists. Tauraco Research Report 5:1–322. Close , 57 Parker, V. (1999). The Atlas of the Birds of Sul do Save, Southern Mozambique. Avian Demography Unit and Endangered Wildlife Trust, Cape Town and Johannesburg, South Africa. Close ) and Angola (58 Mills, M., and M. Melo (2013). The Checklist of the Birds of Angola/A Lista das Aves de Angola. Associação Angolana para Aves e Natureza (AvesAngola), Luanda, Angola and Birds Angola (www.birdsangola.org). Close ), although it might be expected to wander occasionally to these countries, as there are nearby records in adjacent states.

The total range of the species has been estimated at about 2.16 million km² (59 BirdLife International (2021). Species factsheet: Tadorna cana. Downloaded from http://www.birdlife.org on 4/05/2021. Close ) and the core region at ca. 340,000 km² (44 Geldenhuys, J. N. (1981). Effect of temperature and rainfall on the distribution of the South African Shelduck Tadorna cana. South African Journal of Zoology 16:167–171. Close ).

Introduced Range

Occurs in low numbers throughout Europe; from Portugal and Spain in the south, to Czechia to the east, and Scotland and Sweden to the north (eBIrd 2023). Feral birds have bred in the wild in the United Kingdom, although some of these cases may have involved hybrids (60 Ogilvie, M., and the Rare Breeding Birds Panel (1999). Non-native birds breeding in the United Kingdom in 1997. British Birds 92(9):472–476. Close , 61 Holling, M., and the Rare Breeding Birds Panel (2011). Non-native breeding birds in the United Kingdom in 2006, 2007 and 2008. British Birds 104(3):114–138. Close ).

The South African Shelduck has apparently doubled the size of its distribution since the 1800s; historically it was apparently restricted to central and western South Africa, and was previously absent from Namibia, southeastern Botswana, parts of the Western Cape Province, and western KwaZulu-Natal, in all of which regions it is now regular (62 Gill, E. L. (1952). Some first records for the Cape. Bokmakierie 4:27–29. Close , 63 Clancey, P. A. (1967). Gamebirds of Southern Africa. Purnell and Sons, Cape Town, South Africa. Close , 43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close , 29 Allan, D. G. (2005). South African Shelduck Tadorna cana. In Roberts Birds of Southern Africa. Seventh Edition. (P. A. R. Hockey, W. R. J. Dean, and P. G. Ryan, Editors), The Trustees of the John Voelcker Bird Book Fund, Cape Town. pp. 93–95. Close ). The species was apparently absent from areas within ca. 80 km of Cape Town prior to the mid 1920s, and only became common in this area subsequently (62 Gill, E. L. (1952). Some first records for the Cape. Bokmakierie 4:27–29. Close ). Key early accounts either expressly state the species to absent from Namibia or do so by implication by failing to mention the species (e.g., 64 Andersson, C. J. (1872). The Birds of Damaraland. John van Voorst, London, UK. Close , 65 Stark, A., and W. L. Sclater (1906). The Birds of South Africa. Volume 4. R. H. Porter, London, UK. Close , 66 Horsbrugh, B. (1912). The Game-birds and Water-fowl of South Africa. Witherby and Co., London, UK. Close , 67 Hoesch, W., and G. Niethammer (1940). Die Vögelwelt Deutsch-Sudwestafrikas namentlich des Damara- und Namalandes. Journal für Ornithologie 88(Supplement). 404 pp. Close , 35 Delacour, J. (1954). Waterfowl of the World. Volume 1. Country Life Books, London, UK. Close ). The first records in Namibia included three on the Great Fish River, near Seeheim, in January 1950, and a report it was ‘fairly common, usually in small parties’ on Voightsgrund Dam, in February 1950 (68 Macdonald, J. D. (1957). Contribution to the Ornithology of Western South Africa - Results of the British Museum (Natural History) South West Africa Expedition, 1949-50. Trustees of the British Museum (Natural History), London. Close ). Other early records were from the Orange River Mouth, where common, and Konkiep Spring, both during the period 1956–59 (69 Maclean, G. L. (1960). Records from southern South-West Africa. Ostrich 31(1):49–63. Close ), with breeding near Mariental and a flock of about 240 at Goreangab Dam, near Windhoek (63 Clancey, P. A. (1967). Gamebirds of Southern Africa. Purnell and Sons, Cape Town, South Africa. Close ). All of these early localities are from central and, especially, southern Namibia. Winterbottom (70 Winterbottom, J. M. (1971). A Preliminary Check-list of the Birds of South West Africa. South West Africa Scientific Society, Windhoek, Namibia. Close ) stated that the species occurs as far north as Sandwich Harbour and Etemba (northeast of Windhoek) as a common and at least partial migrant in winter. The evidence for an increase in southeastern Botswana is particularly well documented (43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close , 49 Tyler, S. J. (2020). Changing status of South African Shelduck (Cape Shelduck) Tadorna cana in Botswana. Babbler 66:4–10. Close ). The first record from Botswana was from the 1960s (71 Smithers, R. H. N. (1964). A Check-list of the Birds of Bechuanaland Protectorate and the Caprivi Strip. Trustees of the National Museum, Salisbury, Southern Rhodesia. Close ), and there were only two records (from Gaborone) during the first half of the 1970s (72 Beesley, J. J. S., and N. S. Irving (1976). The status of the birds of Gaberone and its surroundings. Botswana Notes and Records 8:231–261. Close ). In the 1980s it was regular in the southeast as a breeding winter visitor (49 Tyler, S. J. (2020). Changing status of South African Shelduck (Cape Shelduck) Tadorna cana in Botswana. Babbler 66:4–10. Close ), with the first breeding record in September 1982 (73 Hunter, N. (1983). Preliminary notes on bird distribution and rarities in south-east Botswana. Babbler 7:14–20. Close ). By the 1990s it was considered relatively common in this area and present year-round. Records from elsewhere in Botswana are also considered to have become more frequent during 2000‒20 (49 Tyler, S. J. (2020). Changing status of South African Shelduck (Cape Shelduck) Tadorna cana in Botswana. Babbler 66:4–10. Close ). The evidence for a widespread increase in KwaZulu-Natal is similarly unequivocal. A flock of seven birds recorded at Underberg in 1962 (74 McCulloch, D. (1962). Shelduck and Maccoa Duck at Underberg. Natal Bird Club News Sheet 93:2. Close ) may represent the first confirmed record for KwaZulu-Natal. Two early specimen records in KwaZulu-Natal (75 Chubb, E. C. (1912). I.-On some birds in the Durban Museum. Journal of the South African Ornithologist's Union 8(1):1–4. Close ), one from 1893, are thought to require confirmation (76 Clancey, P. A. (1964). The Birds of Natal and Zululand. Oliver & Boyd, Edinburgh & London, UK. Close ) but may be acceptable. The first apparent breeding record from KwaZulu-Natal was from the Mooi River in 1966 (77 McCulloch, D. (1967). South African Shelduck breeding in Natal. Natal Bird Club News Sheet 143:1. Close , apparently overlooked by 78 Davies, G. B. P. (2011). Additions, deletions and corrections to the breeding avifauna of KwaZulu-Natal, South Africa, with comments on average clutch size trends and demographic influences. Annals of the Ditsong National Museum of Natural History 1:133–164. Close ). The species was regular and fairly widespread in western KwaZulu-Natal in the 1970s (79 Cyrus, D., and N. F. Robson (1980). Bird Atlas of Natal. University of Natal Press, Pietermaritzburg, South Africa. Close ) and has subsequently expanded even further east in the province (43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close , Second Southern African Bird Atlas Project). Regular records from the Durban area (since about the early 1990s) may emanate from escaped birds (80 Anonymous (1993). Biannual wildfowl counts. Albatross 313:3–4. Close ), although records date back to the 1960s (81 Cooper, P. (1965). Shelduck at the Happy Valley sanctuary. Albatross 121:1 Close , 82 Lawson, W. J. (1971) Check list of the birds of Durban. South African Avifauna Series, Percy FitzPatrick Institute of African Ornithology 73:1–80. Close ).

Information from the First Southern African Bird Atlas Project (SABAP1), largely based on data from the late 1980s and early 1990s, showed that the species had a clearly defined core range, where it was particularly abundant, within its overall distribution (43 Harrison, J. A., D. G. Allan, L. G. Underhill, M. Herremans, and A. J. Tree, Editors (1997). The Atlas of Southern African Birds. Volume 1. Non-passerines. BirdLife South Africa, Johannesburg, South Africa. Close ). This area corresponds to southern parts of inland western South Africa, i.e., in the Western, Eastern, and Northern Cape Provinces, and southern Free State Province. There was a pattern of overall increasing abundance with increasing latitude towards the southern core of the range. A comparison of SABAP1 information with that from the Second Southern African Bird Atlas Project (SABAP2), which was initiated from 2007 onwards, shows a marked shift in the distribution and relative abundance of the species in the South African core of its range (SABAP1/2 comparison). An extension of range, and an even more striking overall increase in relative abundance, has been noted in the east, with a corresponding overall decrease in abundance in western and central South Africa. It remains to be determined whether this represents a response to short-term climatic cycles, or is a longer-term change in status.