Lethal territorial aggression in a white-handed gibbon.

During an intergroup conflict an adult male white-handed gibbon (Hylobates lar) from one group was attacked and wounded by the adult male of a neighboring group. The wounded male's calling behavior, general activity level, feeding, and participation in territorial defense declined dramatically in the days following the injury as he instead spent long periods resting and tending the wound. The normal and healthy appearance of this male prior to injury, the circumstances of the fight that caused the injury, the resultant deterioration in normal maintenance and social behavior, and finally the apparent infection of the wound by insect larvae all suggested that his disappearance 24 days later was the result of death due directly or indirectly to the wound he had suffered. The observations reported here suggest that the ritualization of territorial aggression in this species has not eliminated risks of serious injury and death. © 1993 Wiley-Liss, Inc.