Mammals of the Guinea–Congo rain forest

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SynopsisThe species composition, and the number of species of mammals, in the Guinea–Congo rain forests varies with locality. The highest species richness (up to 130 species) is found in parts of the West Central and East Central rain forest regions, and the lowest richness occurs in the Western Region and on the periphery of the rain forest zone. Rodents and bats contribute the greatest number of species (about 25% each), with lesser numbers of primates, duikers, and small insectivores; the relative numbers within each order is similar in all localities regardless of the composition and total numbers of species. The geographical distribution of each species is due to the alternating periods of forest fragmentation and expansion in the past, and the species-specific response to these environmental changes. There are about equal numbers of arboreal (30%), terrestrial (35%) and aerial (27%) species, each species within these categories having very specific habitat requirements within the forest. Most rain forest mammals are either frugivores (36%) or insectivores (37%): monkeys are mainly arboreal frugivores and folivores, and most prosimians are arboreal insectivores; forest duikers are terrestrial frugivores, and terrestrial rodents are frugivores or omnivores. Leaves, in spite of their abundance, are rarely eaten because of their low nutritive value and the difficulties of digesting them and consequently folivores (9%) are uncommon. Insects form the principal food for insect-bats and shrews. Mammals exhibit well-defined food partitioning in relation to food selection and body size, and therefore competition for food is probably minimal except during the dry season. Reproduction is more or less continuous in rodents and artiodactyis (with peaks of births at selected seasons); in contrast, monkeys and bats have fairly precise periods when births occur, which vary according to the species. The timing of reproductive events is regulated by the rainfall regime, availabiiity of food, and phyiogenetic characteristics such as the length of gestation and body size. Mammals interact with other rainforest organisms, principally as primary and secondary consumers, pollinators, and dispersers of fruits and seeds. Most species of rain forest mammals are solitary, but a few live in monospecific groups or in polyspecific groups. Forest disturbance in recent years (especially forest clearance and hunting) has had very detrimental effects on the geographical distribution and numbers of individuals of all species of forest mammals.