The dynamics of the daily round of the harvester ant colony (Pogonomyrmex barbatus)

Abstract Colonies of the red harvester ant, Pogonomyrmex barbatus, do various tasks outside the nest. There is a daily temporal pattern in the numbers of ants engaged in each of five activities: foraging, nest maintenance, patrolling, midden work and covening. Perturbations were carried out in the field to investigate how the daily round changes in respose to environmental events and colony needs. Intefering with nest maintenance, foraging or both caused changes in the temporal patterns in all five of the observed activities. Temoving nest maintenance workers, foragers or both caused the numbers involved in all five activities to decrease, and there were temporal patterns in the effect of removals. The results of both interference and removal experiments show that the extent to which a worker group does one activity affects the behaviour of other groups. When nest maintenance or foraging is impeded experimentally, these two activities are of reciprocal priority. When both are impeded, foraging is of higher priority than nest maintenance.