ON THE FOOD SHARING AMONG FOUR SPECIES OF ANTS IN A SANDY GRASSLAND : I. FOOD AND FORAGING BEHAVIOUR

Abstract

The purpose of this paper is to study the interspecific food sharing in ants, an important process giving them opportunities to coexist. A grassland on the campus of the Kyoto University where four species of ants, Formica japonica, Camponotus japonicus, Tetramorium caespitum and Messor aciculatum coexisted was selected as for investigation. Direct observations were made throughout the seasons of 1968. Messor, foraging from autumn to winter, fed mainly on the seeds of plants and occasionally on insects. The other three species, foraging from spring to autumn, had similar foraging activities, and their foraging ares overlapped. These ants fed mainly on insects, incidentally on spiders, earthworms and small land snails, although in October Tetramorium mainly fed on the seeds of plants. The components of the food animals in each species were similar, but their weight range differed widely. When individuals of some species were on their way back to the nest carrying food, they were frequently deprived of this food by other species. Considering these weight differences and the phenomenon of interspecific deprivation, a hypothesis is presented that these ants utilize available food in parts by sharing it through the mechanism of interspecific deprivation.