Uncomfortable protection: Formica polyctena Först. shelters Formica fusca L. from Formica sanguinea Latr. (Hymenoptera: Formicidae)

The wood ant Formica polyctena Först. is a territorial species, a regular top dominant of ant communities in forests. Its colonies defend their whole foraging areas (territories) against other territorial ants, including F. sanguinea Latr., a common facultative slave-maker. The most frequent 'victim' of F. sanguinea is F. fusca L., a ubiquitous submissive ant species. On the basis of some earlier observations, the presumption was made that F. polyctena, when defending its own territories, would indirectly protect F. fusca colonies, which nest within these territories, from F. sanguinea raids. It was expected that F. fusca should be more abundant in F. polyctena territories, than in F. sanguinea territories, while other subordinate ants, which are not potential slaves of F. sanguinea, should not show such difference. This hypothesis was supported by the results of the baiting experiments carried out in the Białowieża Forest, NE Poland. The findings are discussed in the context of interspecific competition hierarchy in ants.