I was just about to upload a similar pic that I snapped, but this one is so much better. Well done!
Apparently the female has been more active of late and thus is now fed outdoors. In fact, in one of my pics I actually caught a keeper wandering around at the back with a bucket.
That's the secret - you have to break the rules to get a successful photo. I thought that ZooChatters always went the other way to get to RotRA as quickly as possible.
Many years ago, there was a 3 part BBC series called "Congo", and in one of the episodes the film-makers showed a book of African animals to tribes people in the Congo, to see if they could identify the mokele-mbembe. When they saw a picture of a White Rhino, they all started shouting and pointing. Mokele-Mbembe is/was the Northern White Rhino.