Soil-eating of Japanese macaques (Macaca fuscata) at Arashiyama, Kyoto

概要

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Soil-eating (geophagy) behaviors of Japanese macaques were observed at Arashiyama Monkey Park, Kyoto. They eat soils about once a day or so and seem to prefer rather young soils to mature or senile soils. The soil samples for chemical analysis were collected from Arashiyama, as well as from Takasakiyama and Kohshima monkey parks. Their pH, electrical conductivity, cation exchange capacity, organic matter, inorganic phosphorus and extractable minerals, i. e. calcium, magnesium, sodium, potassium and iron contents were measured. Mineral contents of the soil samples are low and the differences in their values among samples at eating spots and those at non-eating spots in the same monkey park are not detected. Moreover, the differences among monkey parks exceed those between eating and non-eating soil samples.Japanese macaques often eat soils together with another individuals. In such co-eating episodes, intimate individuals, such as a mother and her infant, or two or more juveniles of the same age often form co-eating party. It is expected that Japanese macaques eat soils at the selected spots because of their co-feeding custom and that the supply of minerals such as calcium, magnesium and sodium is not so seriously important, although the possibility of intake of essential rare minerals is not ruled out.
日本霊長類学会の論文