Comparison of seed dispersal by guenons in Kenya and capuchins in Panama

Abstract

We should like to draw attention to differences we have observed between the ways some New and Old World forest monkeys handle fruits and the seeds they contain. We believe that these differences imply different roles for monkeys in their forest ecosystems, and may represent different sets of selection pressures on fruit-bearing plants in African and South American forests. Monkeys disperse seeds in both Africa and Latin America. Jackson & Gartlan (1965) showed that vervet monkeys carried seeds to termite mounds in grassland adjacent to the forest in Uganda, and so caused the spread of forest into grassland. Lieberman et al. (1979) found that baboons disperse seeds in dry forest in Ghana. Gautier-Hion et al. (1985) describe about 40 species of plants as dispersed by Cercopithecine monkeys in a Gabonese rain forest. Monkeys known to disperse seeds in New World rain forests include howlers (Chapman 1989, Estrada & Coates-Estrada 1986, Hladik & Hladik 1969, Howe 1980), tamarins (Hladik & Hladik 1969, Garber 1986), spider monkeys (Chapman 1989, Hladik & Hladik 1969, Howe 1980), and capuclhins (Chapman 1989, Hladik & Hladik 1969, Janson et al. 1986). Monkeys eat a wide range of fruits of different shapes and sizes, and it is unlikely that they could be effective agents of dispersal for all of the species that they consume. The quality of dispersal offered to a particular fruit species by a particular animal depends onthe animal's behaviour, physiology, and morphology: food handling, processing, and gut passage time affect the viability of a seed after the animal is finislhed with it and the size of the clump in which it is deposited; ranging and movement patterns affect where a seed is likely to be deposited with respect to microhabitat conditions and the prevalence of natural enemies, and therefore the fate of the seeds and seedlings (Howe 1989, Janzen 1983, Levey 1987, Lieberman & Lieberman 1986). In this note we consider mainly the first phase of seed dispersal: the removal of seeds from the parent tree and subsequent deposition. Variation in patterns of remzoval and