Justification of Red List Category
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 may be moderately small to large, but it is not believed to 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 overall trend is suspected to be increasing (Wetlands International 2006).
Behaviour This species is largely sedentary, but can be somewhat nomadic and dispersive within its southern African range (Scott and Rose 1996). There may also be some true seasonal north-south migrational movements through central South Africa (South African birds have been recovered in Namibia up to 1,650 km away) (Scott and Rose 1996, Kear 2005b). Its movements are poorly understood (Scott and Rose 1996, Hockey, et al. 2005), although migration appears to be between winter- and summer-rainfall areas (Hockey, et al. 2005) and is dependent on water availability, whereas nomadic movements are believed to be responses to food availability (Hockey, et al. 2005). In much of its range this species breeds throughout the year, although in some areas breeding is more seasonal (for example the breeding peak for birds in the south-west of Cape Province, South Africa is August-December) (Kear 2005b). The species breeds in single pairs or loose groups, but may crowd together where suitable nesting sites are scarce (Brown 1982, Madge and Burn 1988). Outside the breeding season the species is usually found in small groups, or very rarely in numbers up to 600 (Madge and Burn 1988, Kear 2005b). Adult birds undergo a period of moulting after breeding during which they are flightless for around 30 days (Brown 1982); during this time they seek the refuge of large open waters (Brown 1982, Scott and Rose 1996) rich in natural foods (Brown 1982). It is both a diurnal and nocturnal feeder (Brown 1982). Habitat This species shows a preference for shallow freshwater and brackish habitats, such as lakes, marshes and temporary floodwaters (Johnsgard, 1978, Brown 1982, Kear 2005b). It will feed in fertile waters rich in planktonic organisms such as sewage disposal ponds, and will also tolerate highly alkaline lakes (pH 10), tidal estuaries, saline lagoons and salt-pans (Johnsgard, 1978, Brown 1982, Scott and Rose 1996, Hockey, et al. 2005, Kear 2005b). It generally avoids deep lakes, fast-flowing rivers, farm dams and reservoirs except as temporary refuges (Johnsgard, 1978, Brown 1982, Madge and Burn 1988, Kear 2005b). Diet This species is omnivorous, commonly consuming the stems and seeds of water plants, snails, insects, molluscs, crustaceans and amphibian larvae (Brown 1982). Animal matter makes up a significantly larger proportion of its diet than does plant matter (Brown 1982). Breeding site The preferred nesting sites of this species are close to highly fertile shallow-water areas that have abundant sources of invertebrate food (Johnsgard, 1978, Kear 2005b). The nest itself is a shallow scrape in earth, often with sides and a canopy built up from vegetation, and it is generally positioned near the waters edge (Johnsgard, 1978, Madge and Burn 1988, Kear 2005b).
The only known potential threats to this species are the reduction of suitable ephemeral wetland habitats (Kear 2005b), and hybridisation with invasive Mallard Anas platyrhynchos (Hockey, et al. 2005). The species is also susceptible to avian botulism, so may be threatened by future outbreaks of the disease (Blaker 1967, van Heerden 1974). Utilisation This species is hunted, and although hunting is not currently a threat, it has the potential to become one if not managed sustainably (Little, et al. 1995, Kear 2005b).
Text account compilers
Ekstrom, J., Butchart, S., Malpas, L.
BirdLife International (2019) Species factsheet: Spatula smithii. Downloaded from http://www.birdlife.org on 06/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/12/2019.