Primate Behavioral Ecology

Geographic Range

The majority of primates are found within 20 degrees north and south latitude of the equator. They primarily inhabit the continents and surrounding islands of Africa, Asia, and South America. One species of monkey, the Barbary macaque, is native to Gibraltar; however, it is believed to have been introduced by the Romans and, in modern times, restocked by the English. Primates, while largely confined to the tropics, also inhabit more temperate regions.

Forest-Living Primates

Forests can be divided and categorized according to their stage of development and/or regeneration (e.g., primary forest, secondary forest, forest edge, disturbed areas). While primates have specific habitat requirements, some species' requirements are more stringent than others. For example, those species that locomote via brachiation (i.e., swinging by their arms) typically require primary forest. Other species are more adaptable and can inhabit a variety of forest types and possibly even disturbed areas. In the area of Costa Rica where I conduct research on howler monkey-feeding ecology, spider monkeys are found only in areas where the forest is continuous. Howler monkeys, conversely, can be seen in trees alongside roads in beach communities and traveling along electrical wires. Other species that do well in disturbed areas include species of langurs, macaques, and marmosets.

Tropical Forest

Most of the world's primates inhabit tropical forests. Primarily, forest-dwelling species are arboreal in nature. Tropical forests can be classified by the amount of rainfall they receive, ranging from rain forests to dry forests. Rain forests experience little seasonal variability and rain falls year round. There is high species diversity but low species density. Thus, in a given unit of land, for example, many tree species [Page 1930]will be present but at low numbers. Tropical forests that are not categorized as rain forests exhibit a greater degree of seasonal variability, in having both wet and dry seasons, and have lower species diversity but higher species density.

Primates are, to varying degrees, insectivorous and/or herbivorous. The degree of seasonality in a given area thus affects what is available as food at any point in time, since the life cycles of many insect and plant species are correlated with climatic conditions. Even in rain forests, where conditions are more stable, plant production cycles and the patchy nature of food resources affect food abundance and availability for primates.

Tropical forests contain a variety of habitats where primates are found. Some species have very specific habitat requirements. For example, Allen's swamp monkey inhabits swamp forests of central Africa; proboscis monkeys are found adjacent to water on the island of Borneo; mountain gorillas inhabit cloud forest areas of central Africa; and certain genera of sakis and uakaris are found only in the seasonally flooded Amazonian forests.

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