Gorilla

Behavior

Gorillas live in groups called troops. Troops tend to be made of one adult male or silverback, multiple adult females and their offspring. However, multiple-male troops also exist. A silverback is typically more than 12 years of age, and is named for the distinctive patch of silver hair on his back, which comes with maturity. Silverbacks also have large canine teeth that also come with maturity. Both males and females tend to emigrate from their natal groups. For mountain gorillas, females disperse from their natal troops more than males. Mountain gorillas and western lowland gorillas also commonly transfer to second new groups.Mature males tend to also leave their groups and establish their own troops by attracting emigrating females. However, male mountain gorillas sometimes stay in their natal troops and become subordinate to the silverback. If the silverback dies, these males may be able to become dominant or mate with the females. This behavior has not been observed in eastern lowland gorillas. In a single male group, when the silverback dies, the females and their offspring disperse and find a new troop. Without a silverback to protect them, the infants will likely fall victim to infanticide. Joining a new group is likely to be a tactic against this. However, while gorilla troops usually disband after the silverback dies, female eastern lowlands gorillas and their offspring have been recorded staying together until a new silverback transfers into the group.
Nesting
Gorillas construct nests for daytime and night use. Nests tend to be simple aggregations of branches and leaves about 2 to 5 ft (0.61 to 1.52 m) in diameter and are constructed by individuals. Gorillas, unlike chimpanzees or orangutans, tend to sleep in nests on the ground. The young nest with their mothers, but construct nests after three years of age, initially close to those of their mothers. Gorilla nests are distributed arbitrarily and use of tree species for site and construction appears to be opportunistic.Nest-building by great apes is now considered to be not just animal architecture, but as an important instance of tool use