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Similar to declines in antelope species across African conservation areas, sable (Hippotragus niger) at Kgaswane Mountain Reserve, South Africa, has exhibited a negative trend in abundance since 2000. To investigate the cause of decline, we assessed three hypotheses: seasonal forage abundance, habitat conditions and interspecific competition. We considered the evidence for each hypothesis by analysing reserve survey data, rainfall records and historical burn data with hierarchical models that incorporated potential density-dependent effects and environmental covariates. After accounting for the effects of sable abundance, we found that sable population growth was most strongly related to the interspecific competition covariates and to waterbuck (Kobus ellipsiprymnus) count in particular. Also, the strength of the relationship was shaped by the trend in sable numbers and whether the population was before or after peak abundance: the strongest indication of interspecific competition occurred after sable had reached peak abundance. The interaction between abundance of sable and that of potentially competing species emphasizes the importance of accounting for density-dependent processes, and in particular longer-term phases in abundance, when judging the roles of other factors that affect species abundance.

Confined to a small region in central Angola, the giant sable antelope (Hippotragus niger variani) experienced a dramatic decline in numbers and is currently one of the most endangered African mammals. In spite of its iconic status, conservation efforts have been hindered by unsustainable hunting and lack of adequate tools to promote its recovery. In this work, we developed a set of 57 microsatellites specific for the giant sable, which revealed depleted levels of genetic diversity and an allele frequency spectrum consistent with a recent evolutionary history characterized by severe population crashes. In contrast, the high number of private alleles exhibited by other H. niger populations from Zimbabwe and Tanzania may suggest the occurrence of reduced levels of gene flow among sable populations. Our microsatellite panel was successfully tested on the roan antelope, Hippotragus equinus, and will prove highly applicable on the characterization of different Hippotragus populations, but in particular for the conservation of the Angolan giant sable antelope.

The giant sable antelope (Hippotragus niger variani), unique to Angola, was feared extinct after almost three decades of civil war. Comparisons of mitochondrial DNA sequences derived from dung samples recently collected in the field and from old museum specimens of certain provenance provide the first documented evidence to date that this enigmatic antelope has survived. Its DNA-led rediscovery in the former combat zone was subsequently confirmed by photographic evidence. The Angolan isolate constitutes a distinct monophyletic group that shows a dramatic population decline from historic levels. It represents a diagnosable conservation unit which is characterised by unique cranial morphological features (Blaine 1922 1922:317–339), a highly restricted range, and the presence of fixed genetic differences in all of its common relatives.