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The population of the endemic Southern Black Korhaan Afrotis afra is suspected to have undergone a greater than 30% decline over the past three generations, qualifying it as regionally Vulnerable.
The species is endemic to the region, being confined to the winter- and mixed winter-summer rainfall areas of the Albany Thicket, Fynbos and Succulent Karoo biomes, and the southern extreme of the Nama Karoo Biome, in South Africa's Western, Northern and Eastern Cape provinces (Crowe et al. 1994, Allan 2005). Records in Limpopo, Gauteng, Free State and northern extremities of Northern Cape are attributable to misidentifications of the Northern Black Korhaan. A comparison of SABAP1 and SABAP2 reporting rates indicates a decrease in 226 of the 284 QDSs in which the species was reported in either project (Hofmeyr 2012). The species has been recorded in 20 IBAs in the region.
The global population size has not been quantified and requires urgent investigation.
Historically described by Stark and Sclater (1906) as very common and certainly the most abundant of all game birds throughout the Cape Colony; by Uys and Macleod (1967) as one of the dominant species of Coastal Fynbos; by Clancey (1973) as locally common to common; and by Hockey et al. (1989) as a common resident. Although the Southern Black Korhaan still occurs at relatively high densities in small patches of optimal habitat, it is now generally scarce and localised, and the population is undergoing a decline. Comparing reporting rates from SABAP1 and SABAP2, populations in Western Cape showed the most widespread reduction in reporting rates (86% of QDSs), followed by Northern Cape (73%), and Eastern Cape (71%). It is unlikely that these declines were an artefact of the change in atlasing protocol (Hofmeyr 2012), as the species is conspicuous.
Coordinated Avifaunal Roadcounts (CAR) data suggest that the Overberg and Swartland populations declined between 1998 and 2010, while a small portion of the Eastern Cape population showed an increase in numbers after a period of initial decline during a similar period (Hofmeyr 2012). These data showed a higher density in Eastern Cape, which may be explained by the smaller extent of habitat transformation in the Karoo, or may be an artefact of greater detectability in Karoo vegetation compared to Fynbos. Overall, based on data from both SABAP and CAR, the population is thought to have declined by greater than 30% since SABAP1 (1987-1993). The confidence in this estimate is medium.
The primary threat to the species is probably habitat loss and degradation due to cultivation (Hofmeyr 2012). Further research is required to understand the reasons for the decline of this species; however, climate change, human disturbance and increased nest predation by corvids may have also played a role (Hofmeyr 2012).
Young et al. (2003) advocated engagement with land-owners to develop and implement appropriate measures to protect large terrestrial birds. Following consultation and discussions with land-owners, the Animal Demography Unit of the University of Cape Town published a booklet titled "Farming for the future: farming sustainably with nature" which includes information on conservation measures to be put in place for large terrestrial bird species such as the Southern Black Korhaan. The conservation of natural veld on farms and the prevention of excessive disturbance of natural veld by livestock are advocated for this species in particular.
Biodiversity stewardship programmes to formalise the protection of key habitats are a priority. Additionally, where possible, degraded or disused lands should be allowed to revert to natural vegetation. Human disturbance and disturbance by domestic animals should also be minimised. Corridors of indigenous vegetation linking isolated patches of natural veld would also benefit this species. Coordinated Avifaunal Roadcounts (CAR) participants should ideally collect basic habitat availability data along the length of routes to improve habitat use models.
* An accurate estimate of the total population is required.
* An evaluation of seasonal habitat use and movement patterns should be undertaken.
* Launch an investigation into the threats facing the species, including climate change, human disturbance and the possible impact of chick and egg predation by Pied Crows Corvus albus and Cape Crows C. capensis.
* Modelling the relationship between atlas reporting rates, CAR data and actual population density would allow more accurate interpretation of future data, and reduce the need for further ground-truthing.