Site B is a bonus feature in Jurassic Park: Operation Genesis after you complete all the missions. There are no fences, no buildings, and no visitors allowed, and there is no such thing as money in this mode, so you don't have to worry about going bankrupt. You can place up to eight hatcheries, and populate the island with a maximum of 60 dinosaurs. Once you create the dinosaurs in this mode, they will simply roam free and live out their lives on your island. Dinosaurs cannot get diseased, and rarely get stressed. As long as the herbivores have enough trees around them, and the carnivores have enough herbivores to hunt, you shouldn't need to place dinosaur feeders. If you plan out your island ecosystem well, you shouldn't have to interact with the dinosaurs in any way. Just sit back and watch.