Living on the edge: Changes in the foraging strategy of a territorial ant species occurring with a rival supercolony – a case study

Territorial strategy in animals is characterized by the monopoly of resources inside a protected area, the territory. The presence of territorial species considerably alters the behavior of co-occurring submissives, as it is known in several submissive ant species living on the territories of red wood ants in temperate regions. On the other hand, as a rule, territorial species cannot share the same territory and usually exclude each other. However, this ‘rule’ is inferred from the almost complete lack of data on the coexistence of rival territorials, and not from observations regarding the effective exclusion or behavioral inhibition of one territorial species by other. In the frame of this study, we investigated the foraging strategy of the territorial red wood ant Formica pratensis that occurred inside a large polydomous system of another territorial ant species, F. exsecta. Formica pratensis colonies outside the supercolony served as control. Within the F. exsecta supercolony, F. pratensis showed the characteristics of a subordinate species characterized by low discovery and exploitation success of artificial food sources. On the contrary, control colonies outside the polydomous system clearly behaved like typical territorials as they successfully monopolized the majority of the baits. In addition, submissive species were more successful around the F. pratensis nests within the supercolony, than outside of it. As suggested by our results, territorial species could co-occur with other territorials given certain plasticity in their behavior and small colony size. Nevertheless, exclusion also happens as proven by our field observations.