The sacred monkeys are mourned at death and given funerals, just as if they were human. We were shown the cemetery.
The guide told us about a few of the monkey deaths that he was familiar with. One had fallen from a tree and died of injuries, another had gotten into a fight.
There was also a human buried there, the man who had begun the preservation of the land for the monkey sanctuary. Other than him, no humans were permitted to be interred here.