Collecting, discarding, and re-collecting of protein-rich food in a natural colony of Camponotus japonicus

Ants are known for their collective intelligence and efficient division of labor. Therefore, observations that seem to contradict these stereotypes are worth reporting. While observing a colony of Camponotus japonicus, we discovered that workers frequently dumped protein-rich food items at a particular spot, while other workers collected the dumped food items and brought them back to the nest. These two counteractive processes were performed simultaneously by the same colony, which indicates possible inefficiency of their collective labor. Discarding a specific type of food to calibrate the nutritional balance of a colony has been previously reported, but we found no reports on re-collecting discarded food. We suspect that this phenomenon might have been an outcome of communication inefficiency within the colony, or that the putative dump site might have served as a temporary deposit of food items before they were redistributed inside the nest.