Due to competition between males for access to females, few wild males breed before they reach 15 years old. Eight and a half months after mating, a female gives birth to one young, which can usually walk within three to six months. Young are usually weaned by three years old, and females can give birth every four years. Upon reaching sexual maturity, between ages seven and ten, young gorillas strike out on their own, seeking new groups or mates. Zoo gorillas may reach sexual maturity before seven years old, and may have young every two to three years.
Gorillas live in groups.
Each group usually contains one or more silverbacks and two to ten females and young. Newly established silverbacks may kill young not sired by them, but otherwise, gorilla family life is mostly peaceful. Bloody battles sometimes occur between silverbacks when they square off to compete over female groups or home ranges. Gorillas spend their mornings and evenings feeding, usually covering only a small area of forest at a time. Today, Africa's growing population puts many pressures on these declining primates.