Intergroup conflict has been suggested as a major force shaping the evolution of social
behaviour in animal groups. A long-standing hypothesis is that groups at risk of attack
by rivals should become more socially cohesive, to increase resilience or protect
against future attack. However, it is usually unclear how cohesive behaviours ...
Intergroup conflict has been suggested as a major force shaping the evolution of social
behaviour in animal groups. A long-standing hypothesis is that groups at risk of attack
by rivals should become more socially cohesive, to increase resilience or protect
against future attack. However, it is usually unclear how cohesive behaviours (such as
grooming or social contacts) function in intergroup conflict. We performed an
experiment in which we exposed young colonies of the dampwood termite,
Zootermopsis angusticollis, to a rival colony while preventing physical combat with a
permeable barrier. We measured social contacts, allogrooming, and trophallaxis
before, during, and after exposure. Termites showed elevated rates of social contacts
during exposure to a rival compared to the pre-exposure phase, but rates returned to
pre-exposure levels after colonies were separated for nine days. There was evidence
of a delayed effect of conflict on worker trophallaxis. We suggest that social contacts
during intergroup conflict function as a form of social surveillance, to check individual
identity and assess colony resource holding potential. Intergroup conflict may increase
social cohesion in both the short and the long term, improving the effectiveness of
groups in competition.
