Foraging activity of competing ants along altitudinal gradient on a high mountain, South Korea

•Myrmica ants are currently abundant in highlands in South Korea.•Aphaenogaster japonica is expected to increase in highlands in future due to global warming.•Competition and foraging activities of two ant species were surveyed in a high mountain.

The population of Myrmica ants, which is most abundant in high altitudinal areas in South Korea, is expected to decrease significantly due to climatic warming, whereas Aphaenogaster japonica population is expected to increase in these areas. The two ant groups are similar in shape, size, and ecology, indicating intensive competition in overlapping areas. To determine the foraging activities of the two groups and their competitions, I investigated the ants at a high mountain (Mt. Gyebangsan) during two ant foraging seasons (2010 and 2011) using pitfall traps and bait traps along altitudinal gradients. Two Myrmica species (kotokui and kurokii) were present between 800 m to 1577 m, whereas A. japonica appeared up to 1200 m. Fights between ants were observed 22 times and fights between these two ant groups were most frequently found. Food discovery speed is higher in Myrmica species than in A. japonica. The food discovery capability and the nestmate recruitment were not different between A. japonica and Myrmica species.

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