Mountain gorillas have a unique way of spending their nights, they create their own beds in the form of nests using branches and leaves. The nests usually measure between 2 to 5 feet wide and each gorilla makes its own. The silverback typically chooses a spot where he can keep an eye on all family members.   Unlike other primates like chimpanzees and orangutans, gorillas prefer to sleep on the ground instead of in tree branches. When gorilla babies are very young, they sleep with their moms, but as they grow older – around three years, they start making their own nests, usually close to where their moms sleep.   The gorillas do not follow a set pattern for building their nightly nests, they use different places, trees, and materials opportunistically. According to scientists, they believe that the gorillas’ nest–building is a form of tool use. They create a new nest every night, even if the family stays in the same place, they usually start making their nests about an hour before it gets dark so that they are ready for a good night’s sleep when it gets dark.