Nonsocial behavior of captive infant gorillas.

Frequencies of eight nonsocial behaviors (object contact, environmental exploration, mouthing, self-directed behavior, display behavior, solitary behavior, rest, and locomotion) were obtained for 20 infant lowland gorillas (Gorilla gorilla gorilla) between 14 and 36 months of age. They lived in 13 groups in 10 zoological collections. Approximately 12 hours of one-zero data were collected on each animal. Behavioral data were analyzed with regard to the following independent variables: rearing history of the focal animal (mother-reared vs. human-reared), time of day (a.m. vs. p.m.), sex of the focal animal, age of the focal animal, and complexity of the physical and social environment. Results indicated significant differences in the frequency of behaviors within each independent variable, including selfdirected behavior, rest, environmental exploration, and display behavior with rearing history. Additional significant differences in the frequencies of behavior were also found, including mouthing behavior and locomotion with infant age.