Aim: Test hypotheses that present biodiversity and endemic species richness are related to climatic stability and/or biome persistence. Main conclusions: Low climatic variability, and especially a degree of stability enabling biome persistence, is strongly correlated with species richness of birds endemic to southern Africa. This probably principally reflects reduced extinction risk for these species where the biome to which they are adapted persisted. Keywords: atmosphere-ocean general circulation model, biome persistence, birds, Cape Floristic Region, climatic stability, Heinrich Events, Last Glacial-Interglacial cycle, species richness.