What challenge did Hume face with the black rhino in comparison to the white rhino when it came to ranching, as noted in the case study?

In the case study, Hume faced a specific challenge with the black rhino in comparison to the white rhino when it came to ranching. The black rhino had a more solitary and territorial nature compared to the white rhino. This made it difficult to establish large breeding herds for commercial ranching purposes, as the black rhinos were less likely to tolerate being in close proximity with each other.