@PAT: A nest cage is placed in the centre of the free-range area. For the first couple of weeks of being introduced to the free-range area, the primates are confined within the nest cage and provided food and water. Thereafter the primates are confined to the nest cage every night and fed there as well. The primates tend to stay within range of the nest cage as it provides them with a sense of security.
It's not quite as simple as that, even though that is the basics of it. You also have to watch the groups structure carefully. Mature offspring might be evicted or start looking for a territory of their own, and non-breeding groups (same sex sibling groups) might split to look for partners. So, while it might be "simple" running it day to day, in the long run it takes a bit more effort and knowledge.