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9.  Hanya G, Matsubara M, Sugiura H, Hayakawa S, Goto S, Tanaka T, Soltis J & Noma N (2004) Mass mortality of Japanese macaques in a western coastal forest of Yakushima.  Ecological Research 19: 179-188.

Abstract.  Mass mortality of wild Japanese macaques (Macaca fuscata Blyth) was observed in a warm-temperate forest of Yakushima, southern Japan.  Demographic changes of eight troops between 1998 August and 1999 August were studied and 56% of macaques disappeared from the five intensively studied troops.  Mortality varied among troops: two troops went extinct, while another troop did not decrease in size and the mortality of other troops were 33-80%.  The variation in mortality among troops was either the outcome of local concentrations of mortality or of inter-troop competition.  The mortality decreased with increasing distance from the two extinct troops and with increasing troop size; these two factors could not be separated statistically.  The direct cause of death was diagnosed as pneumonia for four of five fresh carcasses.  The fleshy fruit production in autumn 1998 was the lowest in 14 years, and macaques had relied on leaves earlier than in usual years.  It was exceptionally hot and dry in the summer of 1998.  The exceptionally poor fruit production and hot summer of this year, with the resulting shortage of high-quality foods, was consistent with the scenario that the mass mortality was due to the poor nutritional conditions.  However, the possibility that epidemics caused the mass mortality cannot be ruled out.  Our findings proved that primates in a seemingly stable habitat experience fluctuations in demographic parameters under natural conditions.

Key words: mass mortality; inter-troop competition; disease; Japanese macaque; Yakushima.

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<Last update: December 5, 2005>