Comparative Ecology of Primates in West Africa

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Purpose of this project is to make clear the adaptation of non-human primates in same and different environments. The primate species and main research field are Erythrocebus patas and Cercopithecus aethiops of Kaka Maloue, semi-arid region in Northern-most Cameroon, and Pan troglodytes verus of Bossou, mixed forest in South-eastern Guinea.Two species of Kala Maloue distribute synpatrically. Patas has the one-male (multi-female) group and forages widely in the most dry area overlapping its home-range with those of adjacent groups. On the other hand aethiops has the multi-male (multi-female) group and stays within the riverine forest. Group males of patas are frequently ousted by the attack of bachelor sales, though thoed of aethiops stay longer. Group structure, foraging pattern and male reproductive success of both species are being analyzed through their comparison.The group of Pan of Bossou is characterized by the tool-using behavior, particularly the hard-nut cracking using hammer. Through its intensive observation development of hammer-using technique and its individual difference were analyzed. For learning skillful technique infants and juveniles must observe mother's and elders' technique, try to manipulate stones, understand the relation among anvil, nut to be cracked and hammer. It takes more than 10 years for using hammer skillfully. Each individual always uses hammer in his/her preffered hand. About half of individuals of the group is the right hand user and others are the left hand users.However, a few immatures sometimes changed their hand for using hammer. Laterality of hand use develops according to development of the hammering technique. Occasionally an old female used another stone putting under the anvil as "a secondary tool" for its effective use.