Density of herbaceous plants eaten by gorillas in Gabon: some preliminary data

Abstract

Herbs belonging to two families of monocotyledonous plants (Zingiberaceae: ginger family, and Marantaceae: arrowroot family) are important components of the lowland gorilla (Gorilla g. gorilla) diet in Gabon and other areas of tropical Africa (Schaller 1963, Jones & Sabater Pi 1971, Tutin & Fernandez 1985, Calvert 1985). These plants are also consumed by other large forest herbivores such as the chimpanzee Pan troglodytes (Jones & Sabater Pi 1971, Sabater Pi 1979, Tutin & Fernandez, 1985), the pygmy chimpanzee Pan paniscus (Kano 1984, Wrangham 1986), the mandrill Mandrilhs sphinx, and the elephant Loxodonta africana (M. E. Rogers and E. A. Williamson, pers. obs.; Wing and Buss 1970). Browsers, including the buffalo Syncerus caffer and antelope (e.g., bongo Tragelaphus euryceros and duiker Cephalophus spp.) are probably also consumers, and primates normally associated with the canopy may partake on occasion (Cercopithecus nictitans, Bullock 1981). Thus, these herbs are a crucial food resource in African rain forests, and they support a large biomass of vertebrate herbivores. Insect damage to their young leaves is also evident (Letouzey 1972, pers. obs.). Zingibers and Marantaceae (hereafter referred to collectively as THV, terrestrial herbaceous vegetation) seem to represent a superabundant food source, available all year, which could be an important buffer for generalist herbivores against seasonal shortages of other preferred foods such as fruit (Hladik 1973, Tutin & Fernandez 1985).