Territoriality in the Malaysian giant ant Camponotus gigas (Hymenoptera/Formicidae)

Abstract

In a 5-ha area of primary lowland rain forest in Borneo, we observed four polydomous colonies of the night-active giant ant Camponotus gigas. The nonoverlapping, three-dimensional territories in the canopy had a ground size up to 0.8 ha. C. gigas showed a distinct territorial behavior: (1) specific “barrack” nests, especially containing many majors, were situated at the borders and were established during long-term territorial conflicts; (2) trunk trails were regularly patrolled by majors that attacked alien conspecifics and some other ant species violently; and (3) sentinels, often involved in long-enduring conflicts with neighboring ant colonies, defended the borders at bridgeheads. Interspecific conflicts with sympatric Camponotus species always led to violent, “bloody” fights of all castes. Intraspecific conflicts, however, were solved by ritual fights (“front leg boxing”) of majors. C. gigas performed a de-escalation strategy to end short periods of true intraspecific “ant war” that we provoked experimentally. Artificially induced ritualized combats continued over weeks also in the absence of baits, indicating that borders may become established by long-term conflicts of attrition. We discuss the differences between ritual fights in desert and rain-forest ants and apply Lanchester's theory of battles to our findings.