Justification of Red List Category
This species has been uplisted to Vulnerable as recent estimates suggest it may have undergone a very rapid recent population decline. The population in east Africa has undergone a severe long-term decline, but until recently this was thought to have been balanced by increases in southern Africa. The recent trend in South Africa suggests that this population is also now declining rapidly and the global status has been revised accordingly. It remains unclear whether this recent trend represents a sustained decline or part of a longer-term fluctuation, but it is precautionarily assessed as a decline until further data become available. Precise drivers of the recent decline are uncertain but likely include pollution and the drainage and conversion of wetlands.
The population in East Africa has been estimate at 2,000-3,500 individuals (Berruti et al. 2005, 2007), but the severe decline has led to a population possibly as low as <300 individuals. The total population for southern Africa has been estimated at approximately 7,000-8,250 individuals. The total population may therefore number c.7,300-8,500 individuals, roughly equivalent to 4,866-5,666 mature individuals, rounded here to 4,900-5,700 mature individuals.
The northern population of this species has suffered severe declines, perhaps by 50% in the late 1990s to early 2000s (Berruti et al. 2007), with the species now nearing extirpation in some countries (e.g. Kenya [D. Turner in litt. to P. Ndang'ang'a 2016]).
Analysis of International Waterbird Census (IWC) data from Southern Africa indicated a population growth rate of 0.9461 (SE 0.0151) for the period of 1999-2012 (Nagy et al. 2014). Preliminary results of the trend analysis based on the IWC data from Southern Africa for the period of 1991-2015 shows an overall stable population (growth rate: 1.0093, SE 0.0243) for the 25 year period. However, it confirms that the earlier increase was followed by a rapid decline in the last 10 years (0.9341, SE 0.0805, n.s.) that suggests a c. 78% decline over the last 10 years (S. Nagy in litt. 2017; Nagy & Langendoen in prep). Comparison of the results of the first and second South African Bird Atlas Project (Underhill and Brooks 2016) also suggest a substantial decrease has taken place
This information suggests that the overall population is now undergoing a rapid decline of 30-49% in three generations (18 years).
Oxyura maccoa has a large range, divided into a northern population occurring in Eritrea, Ethiopia, Kenya and Tanzania, and a southern population found in Angola, Botswana, Namibia, South Africa and Zimbabwe (Berruti et al. 2005, 2007).
The East African population has been estimated to number some 2,000-3,500 individuals (Berruti et al. 2005, 2007), with the Ethiopian population maybe as high as 500-2,000. However, the population in Kenya is in severe decline with only 14 individuals observed during a survey from December 2014 to July 2015 (G. Kung'u in litt. to P. Ndang'ang'a 2016), and may now be <50 individuals (D. Turner in litt. to P. Ndang'ang'a 2016); and maybe only a maximum of 100 individuals in Tanzania (D. Turner in litt to P. Ndang'ang'a 2016). Thus the total East African population may now in fact be as low as <300 individuals (D. Turner in litt. to P. Ndang'ang'a 2016).
Behaviour This species is mainly sedentary (Kear 2005) but undertakes some small-scale post-breeding dispersive movements in search of suitable habitat during the dry season (Kear 2005). It is not thought to cover distances greater than 500km (Berruti et al. 2005). Breeding has been recorded in South Africa from July to April, with a peak during the wet season months of September to November (Johnsgard 1978). Further north breeding has been recorded in all months, and appears to be dependent upon rainfall (Berruti et al. 2005, 2007). Breeding occurs in single pairs or loose groups (del Hoyo et al. 1992), with a density of up to 30 birds per 100 hectares (Johnsgard and Carbonell 1996) and with males defending territories as large as 900 square metres (Johnsgard 1978, Johnsgard and Carbonell 1996). During the non-breeding season the species is more congregatory (Berruti et al. 2005, 2007), forming flocks of up to 1000 individuals (Kear 2005).
Habitat Breeding During the breeding season it inhabits small temporary and permanent inland freshwater lakes (Berruti et al. 2005, 2007), preferring those that are shallow and nutrient-rich (Johnsgard 1978, Johnsgard and Carbonell 1996) with extensive emergent vegetation such as reeds (Phragmites spp.) and cattails (Typha spp.) (Johnsgard and Carbonell 1996) on which it relies for nesting. It prefers areas with a bottom of mud or silt and minimal amounts of floating vegetation, since this provides the best foraging conditions (Johnsgard and Carbonell 1996). It also breeds on man-made habitats, such as small farm wetlands in Namibia, and sewage-farm basins (Johnsgard 1978, Johnsgard and Carbonell 1996). Non-breeding Outside the breeding season it will wander over larger, deeper lakes and brackish lagoons (del Hoyo et al. 1992, Berruti et al. 2005, 2007). It is thought to find refuge on the larger lakes while moulting (Berruti et al. 2005, 2007).
Diet This species feeds primarily on benthic invertebrates including fly larvae (Diptera), Tubifex worms, Daphnia eggs and small fresh-water molluscs (Johnsgard 1978, Johnsgard and Carbonell 1996). It will also feed on algae, the seeds of Persicaria and Polygonum (Johnsgard 1978, Berruti et al. 2005, 2007), and the seeds and roots of other aquatic plants (Johnsgard and Carbonell 1996). It forages by diving and straining the benthic substrate with its bill (Johnsgard 1978, del Hoyo et al. 1992).
Breeding Site The species tends to nest over deeper water among emergent vegetation (Berruti et al. 2005, 2007). The nest is usually constructed from reeds and cattails that have been bent down to form a basin (Johnsgard and Carbonell 1996), although old nests of Red-knobbed Coots Fulica cristata may sometimes be used.
Currently the links between population trends and threats facing this species are poorly understood. Pollution is a primary concern, since the species feeds mainly on benthic invertebrates, and is therefore more vulnerable to bio-accumulation of pollutants than other duck species (Berruti et al. 2005, 2007). Habitat loss as a result of the drainage and conversion of wetland areas for agriculture is also a significant threat (Berruti et al. 2005, 2007), as are rapid changes in water level that result from landscape changes such as deforestation and can severely disrupt the breeding activity of the species (Berruti et al. 2005, 2007). There is a high level of accidental mortality from entanglement in gill nets (Berruti et al. 2005, 2007). Hunting and poaching, competition with alien benthic fish and habitat alteration by introduced plants all pose less serious threats (Berruti et al. 2005, 2007).There is at least one record of Ruddy Duck O. jamaicensis in the wild in South Africa, and the species is present in captivity there. It is not know whether this species represents a similar threat through hybridisation as it does to Oxyura leucocephala in Europe, but this potential threat should be monitored closely (Underhill and Brooks 2016).
Conservation and research actions underway
In Kenya and Tanzania approximately 80% of the population is thought to occur in protected areas whereas in southern Africa this figure is much lower, with approximately 20% in South Africa and just 10% in Namibia (Berruti et al. 2005, 2007).
46-51 cm. Male has a black head extending to the hindneck and throat. Bright blue bill. Chestnut body and short, stiff black tail often held erect. The female is largely brown with a pale throat and cheek stripe below the eye and faintly barred flanks. Similar spp. No similar species within the range.
Text account compilers
Ndang'ang'a, P., Bird, J., Martin, R, Butchart, S., Ekstrom, J., Westrip, J., Taylor, J., Symes, A.
Turner, D., Dereliev, S., Nagy, S., Butchart, S., Riddell, I., Berruti, A., Ndang'ang'a, P., Simmons, R., Kung'u, G., Hines, C., Tyler, S., Mondain-Monval, J.
BirdLife International (2018) Species factsheet: Oxyura maccoa. Downloaded from http://www.birdlife.org on 22/06/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/06/2018.