We try to mimic conditions in the wild as much as possible – some species are solitary and housing them with others would cause stress and possible aggression. Orang utans, for example, live solitary lives in the wild. Offspring remain with the mother until they are about 14 years of age and then move on. Males and females come together every 7 years or so for mating and then part. The Slow Loris in the Nocturnal House is another animal that prefers to live on its own.