White rhinos in Europe

Originally Posted by Pertinax

I wonder if its to do with the fact these females were all born where they live now, so have had the same management(and female companions) throughout their life-no stress or disturbance from being moved to other locations and they still live in a herd situation, although its less than half the size it used to be.

Many other parks have even smaller numbers and the zoo-bred offspring have possibly been moved about a lot more. Are there stress/incompatability factors at work in the zoobred offspring?