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Dominance relations among females were studied in a small, well-habituated troop of Yakushima macaques (Macaca fuscata yakuz) in southernjapan. Data were collected using focal animal sampling over a 20-month period. Although the frequency of aggression was much lower than that reported for provisioned groups, and support in agonistic interactions was rare, a clear linear dominance hierarchy was apparent. In each of the four pairs of sisters in the troop the older was dominant to the younger. This is contrary to the pattern commonly reported for provisioned groups of Japanese and rhesus macaques, in which dominance among sexually mature sisters tends to be inversely correlated with age. For each pair of sisters in the study troop the mother was alive and healthy when the younger daughter became sexually active, but no cases were seen of a mother aiding one daughter against another. We therefore conclude a) that the absence of youngest ascendancy was due to a lack of support, rather than a lack of potential allies, and b) that both frequent agonistic support and youngest ascendancy are most likely to occur under conditions where concentrated food resources result in frequent and intense aggression.

A wild Japanese macaque troop decreased in size because the birth rate dropped and infant mortality increased. In the 1989 mating season, the last male left the troop, and the remaining two females joined a neighboring troop. Thus, the troop ceased to exist as an independent troop. A lower limit to troop size may exist, below which a troop cannot effectively defend its range, forcing the females to join a larger troop. 0 1994 Wiley-Liss, Inc.

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I observed estrus in two adjacent troops (A-troop and M-troop) of wild Yakushima macaques during the 1984 mating season. A-troop females showed short and regularly cycling estrus periods, seldom came into estrus simultaneously, and scarcely failed to mate when they were in estrus. In contrast, females of M-troop, which went through troop takeovers during the mating season, demonstrated mate competition and subsequent estrus prolongation. Early in the mating season, con stantlyfour to seven females of M-troop were in estrus simultaneously, competed for troop males (TMs), and some of them failed to mate. Subsequently many non -troop males (NTMs) approached to the troop, estrous females mated with them frequently, and mating harassments by females decreased. Among those NTMs, one dominated all TMs, which was referred to as a troop takeover. Successively three other NTMs dominated both all TMs and the former dominant NTM, and in total, four troop takeovers occurred in M-troop during this mating season. The fe malescontinued to be in estrus during the whole episodes. All the conceived fe malesalso showed prolonged postconception estrus, and they were neither inactive nor less attractive to males. It was suggested that M-troop females increased their opportunity to mate with NTMs by estrus prolongation, at the cost of female-female mate competition, to incite active male intertroop movement and subsequent troop takeovers.

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We have found evidence that wild chimpanzees used stout sticks to dig into one end of a decayed fallen trunk from the side and a long stick with a frayed end to dig into or brush its stump, in the Moukalaba Reserve, Gabon. This type of stick use by wild chimpanzees has not been recorded in any habitat. This finding should contribute to future studies and discussions of variations in tool use and cultural processes among wild chimpanzees.