Adolescent males, on the other hand, usually remain in the troop until they can leave and establish a new troop on their own as the silverback. Troop populations range from 2- 12 individuals, with 9 being the average size. The silverback is typically the most aggressive member of the troop because he is the one who must provide protection and security. He also makes all of the group decisions, settles disputes between members, and gets the majority of the group's food.
Although gorillas typically aren't aggressive, they do exhibit territorial behavior by standing upright on their bottom two legs and pounding their chests in order to intimidate whatever threat they have been given. These gestures, however, are more for show and aren't usually violent. These instances can come about when two silverbacks of different troops meet, when two males are fighting over a female that they want to mate with, or when a younger male is challenging the silverback for dominance of the troop. However, in stable troops these acts of violence and aggression are very rare.
At dusk, gorillas settle down for the night in nests made of vegetation that is shoved around them. These nests are initially made by bending soft trees, breaking bamboo sticks, and taking large leaves from other types of trees to be used as a blanket to shield from the cold. Mothers like to find a comfortable spot in the nest where their backs can be supported so that they can breast feed and cuddle their babies throughout the night.