Abstract
The size of the nesting cavity and the nature of the nest-building material can constrain colony growth in eusocial insects. Rocks protect colony members against extreme temperatures as well as serve as a supplementary source of heat, thereby maintaining optimal conditions for brood development. The frequency distribution of available rocks and those occupied by colonies of Rhytidoponera metallica in the Avon River State Forest, Victoria, Australia, showed that colonies of R. metallica avoided nesting under small rocks (<200 cm2). A strong correlation between colony size and rock size indicates that nesting under a larger rock promotes colony growth. Laboratory choice experiments revealed that workers are capable of recognizing larger rocks from external physical characters (dimension). Field data indicates that colonies leave nests frequently, with nest abandonment peaking in the summer months.
