Cercopithecines

Distribution, Habitats, and Diets

Other than macaque monkeys, all species of wild cercopithecines are restricted to Africa, with one exception: a small population of hamadryas baboons along the southern edge of the Arabian Peninsula. Conversely, macaques are represented in Africa only by Barbary macaques, in the Atlas Mountain region, but in Eurasia by a series of about 15 species extending eastward across southern Asia to various islands of the south Pacific and north as far as the islands of Japan. The distributions of individual species of cercopithecines range in size from part of one peninsula of one Pacific island(Heck's macaque) to large portions of Africa (anubis baboons)and Asia (rhesus).

The habitats of various cercopithecine species differ widely: swamp forest, many other types of forest and open woodland, alpine meadows and bamboo thickets, savannah grassland, even Ethiopian rocky desert, and the Japanese island of Hokkaido, which is covered by snow in winter. A few species are primarily arboreal (for example, dwarf guenons) or terrestrial (patas monkeys, hamadryas, geladas),but most species are both, in varying proportions.

The two subfamilies of Old World monkeys are distinguished by various dental and skeletal features, but of particular ecological and behavioral significance are two distinguishing features of the animals' soft tissues: cheek pouches, found only in cercopithecines, versus a stomach with at least three enlarged fermentation [Page 465]chambers, found only in colobines. The cheek pouches of cercopithecines are used for short-term storage of relatively small but locally concentrated foods that can be harvested faster than they can be orally processed, thus reducing exposure to competition and predation. Later, at their leisure, the monkeys bring the foods back into the oral cavity for processing before swallowing them. Monkeys of this subfamily are sometimes referred to as “cheek-pouched monkeys.”

Few cercopithecine primates are obligate food specialists. Most species can be characterized as eclectic omnivores, in that their foraging is very selective yet their diet is highly diverse. They feed selectively on a great variety of plant and animal foods that are available in their habitat, eating this part of a plant but not that, feeding on the fruit of one species but not that of a similar, closely related species, feeding on fruit that is fully ripe and ignoring fruit that is semiripe, removing acacia seeds from their pods, then the naked seeds from its seed coats, and so on. Baboons represent the extreme development of such highly selective omnivory. Their mastery of this mode of life has enabled them to become the most widespread and abundant primates on the African continent. Selection for traits that lead to such success are still present:among yearling baboons, differences in dietary intake of proteins and energy are accurate predictors of survivorship and lifetime reproductive success.

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