By the 1830s the black wildebeest had been largely cleared from the open highveld, killed both for its hide and because settlers treated it as a pest on grazing land. The species survived only because a few landowners in the Orange Free State and elsewhere kept small herds, and the total is generally reported as having fallen to a few hundred animals.
Recovery came through protection and private-land management rather than a single reintroduction programme. Numbers now run into the tens of thousands, with the majority on private farms and game ranches, and the species is assessed as Least Concern. That listing describes abundance, not genetic health.
The bottleneck left a legacy. The remaining population passed through a narrow founder base, and hybridisation with the blue wildebeest where the two are kept together on ranches produces fertile offspring, which threatens the genetic distinctness of the species more than raw numbers do. Managing separation between the two species is now a live conservation concern in South Africa.