Self-organizing nest construction in ants: individual worker behaviour and the nest's dynamics

We examine nest construction in the ant Leptothorax tuberointerruptus at two levels: (1) the building behaviour of individual workers and (2) the collective properties (temporal and spatial) of the structures they create. We also explore, for the first time explicitly, the linkage between these two levels. Leptothorax tuberointerruptus nests occur in flat cavities which provide the roof and the floor of their dwelling places. Hence, they construct only a peripheral encircling mall, breached by one or more entrance passageways. The wall is constructed brick by brick. This facilitates experimental estimation of the probabilities of individual workers picking up and depositing building material in response to different stimuli. We incorporate both the qualitative and quantitative behavioural rules that workers employ during building into a mathematical model. This model confirms that a surprisingly small and simple set of behavioural rules are not only sufficient for wall construction bu; also for the formation of one or more nest entrances. In addition, this model predicts that the nests of these ants are likely to exhibit interesting dynamics, in which, for example, the tendency to build a new larger nest may lag behind growth of the population that the nest has to house. We present experimental evidence that suggests that this prediction is valid. (C) 1997 The Association for the Study of Animal Behaviour.