Immigration and formation of mixed colonies in red wood ants (Hymenoptera,Formicidae)

Long-term field studies of the composition and spatial structure of settlements of ants of the Formica rufa group were carried out in two regions of Russia (Moscow and Arkhangelsk provinces). Fragmentation of damaged nests followed by reintegration of the fragments is the main way of formation of mixed colonies of ants from different nests (including different species). The principal factor of nest fragmentation is their damage by wild boars, bears, and in some localities, by poachers. The formation of mixed nests and nest complexes with participation of different Formica species was observed. They are formed by joining the ants from several damaged nests or by a colony from a destroyed nest immigrating into an intact one. Regular damage of many nests leads to the formation of broad zones of mixed colonies. The mixed colonies including 2–3 species of wood ants have recently become common. The phenomenon of mixed colonies raises a question as to the relative importance of two basic principles (sociality and specific identity) in the life of ant societies and demonstrates the priority of the social principle.