Unprecedented Behavior Observed in Ants on Kangaroo Island: Are They Dead or Alive?

Polyrhachis femorata ants are a species of hardworking ants known for their new talent - playing dead. Researchers from the University of South Australia discovered a whole colony of these ants feigning death while checking pygmy-possum and bat nest boxes on Kangaroo Island. The researchers believe that this behavior is a defensive strategy adopted by the ants to avoid potential danger, making it a world-first observation. This is the first-ever recorded incident where an entire ant colony of playing dead has been observed, and it is the first record of Polyrhachis femorata ant species in South Australia. The research paper has been published by CSIRO.

Wildlife ecologist, UniSA’s Associate Professor S. ‘Topa’ Petit, who was part of the research team, said that she was surprised to discover a colony of ants lying motionless in one of the nest boxes. She added that this sort of defensive immobility behavior was only known among a few ant species and individual casts, making this observation unique. According to her, nest boxes could be an excellent opportunity to study the ants’ death-feigning behaviors, which are of great interest to many behavioral ecologists investigating the diversity of animal species.

The Kangaroo Island Nest Box Project discovered this behavior while monitoring 901 box cavities across 13 diverse properties. The project was initiated as part of wildlife recovery efforts following the devastating 2020 bushfires. Co-researcher at the Kangaroo Island Research Station, Peter Hammond, revealed that they used to call the Nest Box Project ‘Friends of the Invertebrates’ since invertebrates were often the only occupants of the bat and pygmy-possum nest boxes.

Hammond stated that most of the nest boxes are on burnt ground, but they also have some on unburnt properties, which are used as controls to determine the value of nest boxes in bushfire recovery. Polyrhachis femorata is strongly associated with the critically endangered Narrow-Leaf Mallee community, where it colonized several boxes quickly. However, they also have records of the ants being present in two other properties further west, indicating that the ants will use other habitats. The researchers believe that the bushfires strongly impacted Polyrhachis femorata evolutionary strategy.

The discovery of Polyrhachis femorata playing dead is a thrilling experience for the researchers. They say that though there might be other ants with similar behavior, these discoveries excite them as pioneers in studying ants. The species is beautiful, arboreal, and quite shy, with little else known about its ecology or behavior. Ants in general provide crucial ecosystem services and are a vital part of functional ecosystems on Kangaroo Island and elsewhere. Further research will aim to unveil more about the ecology of Polyrhachis femorata and other unknown species of ants.