The Mountain Gorilla Veterinary Center veterinarians have successfully managed several viral outbreaks that could have eliminated the entire population. In 1988, a widespread respiratory outbreak followed by a suspected measles outbreak led to the immunization of 85 gorillas. Gorillas live in stable groups of two to nearly 40 individuals, led by a dominant male called a silverback. Females usually have their first offspring at about age 11. They are nurturing mothers, who groom and feed their babies.
Infants are totally dependent for three months after birth.
Infant and adolescent gorillas are extremely playful. Gorillas share many activities with little regard to gender. It is common to see silverbacks grooming and playing with infants. Older, adult females will sometimes take part in defending the group in altercations with rival groups. Mountain gorillas eat leaves, shoots, stems and occasionally fruit from 58 different plant varieties.