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Effects of hand-rearing on the behavioral development of infant and juvenile gorillas (Gorilla g. gorilla)
1Institute of Zoology, University of Heidelberg, Federal Republic of Germany.
Insights
Hand-reared gorillas often develop stereotyped behaviors, but these usually fade. Peer group rearing and early introduction to adults can mitigate behavioral differences in young gorillas.
Area of Science:
- Primate Behavior
- Animal Development
- Comparative Psychology
Background:
- Hand-rearing practices in gorillas can impact infant development.
- Understanding developmental trajectories is crucial for captive primate welfare.
Purpose of the Study:
- To compare the behavioral development of hand-reared versus mother-reared infant and juvenile gorillas.
- To identify differences in social behaviors, play, and aggression between rearing conditions.
Main Methods:
- Longitudinal observation over 3 years of 19 hand-reared and 7 mother-reared gorillas.
- Behavioral assessments included social behaviors, solitary play, aggression, and grooming.
Main Results:
- Hand-reared gorillas exhibited more stereotyped behaviors initially, which typically resolved.
- Hand-reared individuals showed increased solitary play and aggression, and decreased social play compared to mother-reared gorillas, especially when housed in pairs.
- Group housing reduced behavioral differences between rearing types.
Conclusions:
- Gorilla infants benefit from rearing in peer groups.
- Early introduction (by one year of age) to adult conspecifics is recommended for hand-reared gorillas.
- Rearing environment significantly influences social and behavioral development in gorillas.
Abstract:
Nineteen hand-reared and seven mother-reared infant and juvenile gorillas were observed for a period of 3 years. Almost all hand-reared individuals developed stereotyped behaviors during the first months. In most cases these behaviors disappeared in the first or second year. Social behaviors, solitary play, nest building and grooming developed at about the same age in hand-reared and mother-reared infants. Hand-reared immatures showed significantly more solitary play, more aggression and less social play than mother-reared ones, especially when raised in pairs. When young gorillas were kept in groups, the frequencies of these behaviors came nearer to those of mother-reared immatures. No significant differences were noted in social play. When introduced to conspecifics, hand-reared infants sometimes reacted with indiscriminant aggression. Gorillas should thus preferably be reared in peer groups and be introduced to adults not later than one year of age.