关键词: 花鼠, 年龄组成, 繁殖

Abstract: This paper reports the population age and reproduction of Eutamias sibircus．202specimens were shot in the Zhongtiao mountains of Shanxi province during March toOctober of 1991．Based on their eye lens weight，the specimens were divided into 4 agegroups.Seasonal changes of the population age structure wereanalysed．This chipmunkreproduced once a year．The gestation period lasted from late-March to mid-April andthe birth period from mid-April to mid-May．The litter size was 5.08
±0.16．The juvenilesborn in early-June．All juveniles born in last year joined breeding after hibernation．
The teeth height index and the degree of molar worn also could be used to dividethe population classes，but eye lens weighewas the most accurate．It was not applicableto estimate the age of this chipmunk by means of the body weight，body length andtail length．

Key words: Eutamias sibiricus, Population age structure, Breeding