PRIMATES, 42(4): 327-344, October 2001 327 Geophagy by the Bonnet Macaques (Macaca radiata) of Southern India: A Preliminary Analysis J. VOROS, W. C. MAHANEY,M. W. MILNER York UniversiO, R. KRISHNAMANI Pondicherry Universi O' S. AUFREITER University of Toronto and R. G. V. HANCOCK Royal Military College of Canada ABSTRACT. Bonnet macaques (Macaca radiata) in the Marakkanam Reserved Forest of southern India consume termitaria soils. Samples from the ingested termite mounds are compared with samples taken from the surrounding uneaten soils in an attempt to determine why the termitaria soils are eaten. Particle size, clay and primary mineral composition, geochemistry, and scanning electron microscopic analyses are used to search for a possible explanation for geophagy among the bonnet macaques. Kaolin minerals abound throughout the Marakkanam soil sample suite. But the termitaria soils are distinguished by the presence of small amounts of smectite. An abundance of kaolin minerals in combination with small amounts of smectite strongly resembles the mineralogy of eko, a traditional African remedy for stomach ailments, and Kaopectate TM, a western anti-diarrhoeal preparation. The percentage of mature leaves and fruits of Azadirachta indica consumed by the bonnet macaques is relatively high. Plant feeding deterrents, such as, acid detergent fibre (ADF) and the inherent nature of the fruits of Azadirachta indica, when con- sumed in large quantities to act as a purgative, could cause gastrointestinal upsets and diarrhoea. At Marakkanam, bonnet macaques ingest termitaria earth that would act as a pharmaceutical agent to allevi- ate gastrointestinal upsets and control diarrhoea. Key Words: Geophagy; Soil consumption; Primates; Bonnet macaques; Macaca radiata. INTRODUCTION Primates have an eclectic diet that is determined by temporal, spatial, anatomical, and physi- ological parameters. These, combined with differences in habitat, produce a wide variety of diets (OATES, 1987). The great majority of primate species eat a combination of leaves, fruits, flowers, and animal matter. They are also observed to eat mushrooms, roots, bark, seeds, and gums; and a mixed diet seems to have been a dominant feature throughout primate evolution (MARTIN, 1990). Sometimes primates have been observed to deliberately eat "vague" items such as charcoal (STRUHSAKER et al., 1997), dead wood (STRUHSAKER, 1975), and soil. The deliberate ingestion of soil is termed geophagy. Geophagic behaviour is prevalent in the animal world, particularly among generalist herbi- vores (JOHNS, 1990; KREULEN, 1985) and primates (KRISHNAMANI& MAHANEY, 2000). Of the 185 species of extant primates, only 39 (21.1%) are reported to ingest soil and 11 (22.4%) of the 49 species of Cercopithecidae primates are observed to engage in geophagy. The number of pri- mates known to indulge in geophagy is increasing, day by day, as more studies on primate ecol- ogy are published (KR1SHNAMANI & MAHANEY, 2000). Soils eaten by nonhuman primates could be occasional and/or regular but constitute only a fraction of their diet.