Age Structure in Mass Mortality in the Sika Deer (Cervus nippon) Population on Kinkazan Island, Northern Japan

抄録

A mass mortality of sika deer (Cervus nippon) population occurred on Kinkazan Island in northern Japan in the spring of 1984, which followed an unusual cold winter. We collected a sample of 240 deer skulls. All deer were aged and sexed except some fawns. The sex ratio of >1 year old deer was 50: 50, but was skewed toward males compared with the sex ratio obtained in the population census in 1983. The oldest age at death was 12.5 years for males and 15.5 years for females. The frequency was low for young age classes. A relative cumulative frequency curve was constructed to examine the age-specific mortality pattern. The curves of both sexes suggested that mortality was relatively high for fawns and low for adult and prime-aged animals, and that mortality was higher and life span was shorter for males than for females.