I think it's a drainage issue. The mound in the centre of paddock is in good condition because the water runs off. But the low part alongside the public path was a real mess when I visited three weeks ago: Patna was having to be very careful in the deep mud near his wallow.
Alan
I just don't think in the longterm the paddock can maintain a pair of rhinos using it and also support the antelope and deer as well. Even if its properly drained the rhinos will cause the grass to die off, causing the mounds to become bare earth and the lower areas a quagmire. (Mind you, Blackbuck aren't found anywhere near rhino in the wild anyway