The effects of habitat loss and fragmentation on the relative abundance and conservation of Southern Black Korhaan Afrotis afra, a South African endemic

Abstract

Southern Black Korhaan is “Vulnerable” to extinction and a South African endemic that is restricted to the area of the Northern Cape Province that is west of the Great Escarpment, and to the area south of the Great Escarpment in the Western Cape, and the western section of the Eastern Cape Province. The 1990, 2014, and 2020 land use land cover (LULC) databases prepared for South Africa were used to determine the LULC categories that best describe suitable habitat for the birds using beta regressions and data on the exact locality of the birds from BirdLasser. The South African Bird Atlas Project (SABAP) reporting rates were used to determine the change in the relative abundance of the birds between the first and second SABAP. Beta regression models were compiled using the bird’s reporting rate and the total surface area, and three other landscape metrics, of the per pentad LULC categories considered to be suitable habitat for them. These models and the SABAP reporting rates revealed that Southern Black Korhaan is adversely affected by the loss of, especially, its fynbos habitat to crop agriculture. In 2020, the area of suitable habitat available to the bird was estimated to be 2,035,526 ha on terrain with a slope of ≤4°. Southern Black Korhaan remains “Vulnerable” to extinction because of the continued decline of >30% in the size of its population over three generations (31 years). The cumulative effects of habitat fragmentation and loss on Southern Black Korhaan and other threatened taxa must be mitigated by conserving and, where appropriate, rehabilitating suitable habitat (e.g. Gouritz Cluster Biosphere Reserve’s Corridors and Rehabilitation Project) in the protected areas, critical biodiversity areas, and ecosystem support areas identified in the provincial spatial conservation plans. Together these areas form a perforated landscape that ensures maximum connectivity between the remaining patches of indigenous habitat.