Behavioral responses of an infant gorilla to maternal separation in a captive social group of lowland gorillas (Gorilla gorilla gorilla)

The present report describes behavioral reactions of a 33-month-old female infant gorilla to maternal separation in a captive social group whose compo sition is similar to that of wild groups. The infant gorilla responded diff erently to two types of maternal separation. When she remained alone for a few hours, she cried repeatedly and moved restlessly, indicating protest. U pon reunion and also for a few days thereafter, an intensification of the m other-infant relationship occurred. On the other hand, when she was separat ed from her mother but remained with the other group members for nine days, she did not display any behaviors that could be characterized as protest, but rather showed clear behavioral depression. During the 9-day separation period, she hardly played with other group members but she developed affili ative relationships with the leading male. After the reunion from the 9-day separation, she spent as much time near her mother as before separation an d played with other infants at a level similar to that before separation, w hile she sometimes displayed behavioral patterns demanding the maintenance of physical contact with her mother. The present findings are compared with other reports in great apes and human children.