Nest relocation in the golden spiny ant, Polyrhachis ammon: environmental cues and temporal castes

Despite its apparent costs, nest relocation is a common phenomenon among ants. Polyrhachis ammon, a common ant in open habitats of eastern Australia, exhibits a high rate of colony emigration to new nest sites. We conducted a field survey and shading experiments in different seasons and years to determine which factors affect colony emigration in this species. We also compared morphological features characterising workers involved in adult transport to determine if workers performing different tasks belong-ed to discernible temporal castes. Nests that were abandon-ed after four weeks were smaller, although distance from a food source and low-level disturbance did not alter re-location rates. The effects of shading and nest temperature on nest survival varied between seasons, as did rates of nest relocation. Transporter workers could not be distinguished from foragers, but had greater mandibular wear and smaller dry mass than transportees. Our results suggest that cues promoting nest relocation in P. ammon may be the result of a combination of factors with varying temporal importance.