Territorial Behavior

Gorillas are highly social, relatively non-territorial and live in groups (called troops) that usually consist of 1-4 adult males, some juvenile males, and several young and adult females.  The oldest and strongest adult male (called the silverback) is usually the dominant one of the troop and has exclusive breeding rights with the females.  Adolescent females transfer to a different troop once they reach about eight years of age. Generally, the first troop in which the female produces offspring becomes her permanent troop.  A female's status is usually determined by the earliness of her entry into the troop.  For instance, latecomers do not get as many benefits, which include protection of offspring by the dominant silverback.  For this reason, females do not have strong relationships with each other because they are constantly fighting to be closest to the silverback in order to receive the most attention and protection.

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. 

Sources:

http://www.seaworld.org/animal-info/info-books/gorilla/behavior.htm

http://www.travelhemispheres.com/uganda-safaris/gorilla-safaris/gorilla5.html

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