Ok this is a bit of an odd one and I have learnt not to do it but... In Sandbox mode I made an enclosure and dug down and made a steep valley with a shelter a pond lots of enrichment and put cheetahs in there... They bred well and were healthy but visitors were not looking at them..... because they couldnt see them. I decided to re-landscape while they were all in there by pulling up the ground and moving the shelter etc. once I accidentally covered an animal and it was boxed up and everything was ok. But gradually one of the adults got more and more stressed. It didn't like the fire hose toy id put in before I re-landscaped.... I couldnt find it, there was no way of selecting it from the animals dialogue box to delete it and I'm sure it was buried somewhere in the enclosure, but I couldn't find it.. well it stressed the animal out so much that eventually she died and there was nothing I could do about it. If it wasn't visible surely it wouldn't cause that much stress. But if i could have selected and deleted it from the animals dialogue box it wouldn't have been a problem.