We contrasted calf survivorship of horned and dehorned black rhino (Diceros bicornis) females in the Namib Desert, and have reported elsewhere that calf mortality was higher in a dehorned population sympatric with spotted hyaenas (Crocuta crocuta) than it was in a hyaena-free area or where mothers were horned. Our findings have been controversial because sample sizes are small and data on some ecological variables were not offered. Here, we clarify our research protocols and substantiate prior findings with comparative data on potentially confounding variables such as horn size similarities, hyaena abundance, patterns of precipitation, herbivore biomass, the location of domestic stock, and adult rhino mortalities. We suggest that management decisions based on empirically-derived data might be better than those based on no data at all.