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

摘要： 1991年3-10月在山西省中条山区猎获花鼠202只。以眼晶体干重为指标划分出4个年龄组，分析了种群年龄组成的季节变化。该鼠每年繁殖1次， 3月下旬-1月中旬怀孕，产仔期在4月中旬-5月中旬，胎仔数5.08±0.16只， 6月上旬幼鼠出现。幼鼠于翌年春季出蛰后参加繁殖。此外，还将晶体干重、齿高指数和臼齿磨损程度3种年龄指标所划分的结果作了比较，也证实体重、体长和尾长不能用于该鼠的年龄鉴定。

关键词: 花鼠, 年龄组成, 繁殖