We were tracking this white rhino bull with guests we caught up with him following a lone female. This face, referred to as the 'Flehmans Grimace' is common amongst many male mammals; they do ths when they are testing females urine in order to determine if she is ready to mate. Most mammals have a special organ at the top of their mouth called the Jacobson organ. When they smell the females urine, the upper lip and teeth are exposed to allow more air in, the air particles are then wafted into the roof of the mouth towards the Jacobson's organ, determining the status of the female. This was the first time I'd seen this fascinating behaviour so clearly in a rhino, what a pose! Let's hope that he does his part for the species, and that soon we hear the pitter patter of baby rhino.