Bongo/bobby looks even smaller in this photo than he was real in life- its just the pose. His time at Bristol wasn't terribly successful, he had grown up in Rome with Romina so never mated with her, and I doubt that he did with Salome either- he seemed to dislike her from what I could see of their behaviour.
A shame he died though as he was mating with two of the ZSL females though he may not have been fertile. I don't know why when he was moved to ZSL, they started to call him 'Bobby' as he had been 'Bongo' all his life up till then.