Twigs in leaf litter: overlap in twig size occupation by nesting ants

Twigs in leaf litter represent an important nesting resource for ant colonies. Twig diameter strongly influences the occupation of twigs by ants, possibly determining the size of colonies. Given that uncolonized twigs are common in leaf litter, we tested the hypothesis that ant species occupy twigs with a similar size (i.e., resource use overlap). In addition, we expected that colony size at assemblage and species levels were related to twig diameter because twig size may hinder nest occupation. We analyzed all twigs present in 112 4 × 4 m plots, summing 1792 m2 of leaf litter in 16 Atlantic Forest sites. We separated the twigs occupied by ants, counted the number of individuals, and measured twig diameter. We recorded 701 twigs occupied by 28 ant species. At the species level, we detected four twig size classes, with preference for twigs between 11.5 and 16.1 mm in diameter. Assemblage-wide, we found a significant relation between colony size and twig size. In addition, many ant species did not show a relationship between colony size and twig size, suggesting that ant species drive the general relationship by selecting different twig size classes.