@Jana The exhibit is apparently very new and I have no idea why it was so muddy as I visited in the dry season with zero rain anywhere. The torrential 'wet season' arrives in a few months and so I'm not sure what the zoo is planning to do with their giraffes. For one thing, the enclosure is far too small for the big herd.
With that many giraffe in that small of an area... I am going to say that is all a result of urine build up. It does not take long for substrate to get sloppy when you have that many animals of that size living on it 24/7, especially in an area where the soil is going to retain water well...
