1957 年 7 巻 4 号 p. 166-171
A horizontal, well sun-shiny area of 16×20 sq. m. in the precincts of a temple, deeply surrounded by trees and shrubs, inhabited by four species of ants-Camponotus herculeanus japonicus MAYR (abbreviated to C), Formica fusca japonica MOTSCHULSKY (abbr. to F), Aphae-nogaster famelica SMITH (abbr. to A) and Tetramorium caespitum jacoti WHEELER (abbr. to T)-was adopted as the observation ground. It was sectioned into a net of 2 m (partly 1 m)meshes and was baited at all corners of the meshes with such small insects as house flies and the like. All the baits were numbered by means of a tiny label respectively which was attached with a silk thread, in order to make clear their original positions even when they were carried afar by the ant. They were always replaced by another new ones as soon as dragged off. Observations were made as to the species and the nest of the ant by which the bait was found and transported. Also every event occurred during the transportation was recorded in detail. The investigation was conducted during 8-10 o'clock a.m. every day from Aug. 3 to 26,1956. The records thus obtained were put in order on a sheet of section paper per species (Figs. 2,4 and 5) and the foraging range of each nest population, its size, form and distribution, as well as its intra-and interspecific relations were investigated. Also the social order among the species concerned could be elucidated through the observation of their behaviour during forage and bait transportation. The results can be summarized as follows : 1) Habitat segregation and territoriality can be observed, as a rule, among nest populations of the same species (Fig. 2,4 and 5). Such relations, however, could not be confirmed, as a rule, between populations of different species, although there can be admitted some tendency towards such a segregation between A and T, A and F and C and A. 2) Foraging distance is greatest in F, next to it in C and much less in A and T, the last mentioned two being nearly equal to each other in the range of their foraging. (Fig. 3). 3) Social order among the species concluded from the observation of the behaviour at the time when they met with one another is A=T>C>F. While the ratio of the total number of the baits carried away by each species is C>T>F>A. However, when the dimension of the ants is taken into consideration, it comes to be efficiently T>F>C>A. Possibly this is the practical scale of the population prosperity among them.