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### 北京地区黑线姬鼠种群年龄和繁殖的研究

• 出版日期:2006-07-29 发布日期:1989-02-20

### ON THE P0PULAT10N AGE AND REPR0DUCTION OF Apodemus agrarius IN BEIJING AREA

ZHANG Jie

• Online:2006-07-29 Published:1989-02-20

Abstract: The popalation ecology of Apodemus agrarius in the rural area of Beijing was investigated from 1982 to 1986. A total number of 1360 specimens were colleced and dissected, among which 684 were males and 676 females．
1．Age struture in population
(1) Division of the age groups the specimens were divided into four age groups based on their body weight excluding viseera as the major index． The body weight of groupⅠ was≤10g； group Ⅱ 10．1一16.9g; groupⅢ 17— 24.9g; group Ⅳ > 25 g．
(2) The seasonal fluctuation of the age structure in Popu1ations：on the basis of analysing our five years trapping data from January to February．we found there wereno individuals belonging to the group IV in the population of this area． From M arch to April．the proportion of group Ⅲinceresed and group I decreased． From May to June, the individuals of group Ⅳ began to appear and increased in number suecessively;whilethe proportion of group I and Ⅲ was remarkably low. During the
months of July and August．the proportion of group 1V， i.e., the individuals of the overwintering mice increased． while the in dividuals of that year belonging to the group I and Ⅲreappeared and increased in number, Group IV decreased in number from
September to October， due to the death of the overwintering mice． In November and December， the main compositions were the in dividuals of gronp Ⅲ and group I， while individuals of group IV were rarely seen．So we can draw a conclusion that the population structure of Apodemus agrarius renewsonce a year in the area．
2． The sex ration: It was approximately 1：1 on the whole， but♀﹥♂in group Iand Ⅲ，and ♂>♀ in group Ⅲ and Ⅳ ．
3． The breeding ecology in population
(1) The breeding characteristics of the males．Studies have been carried out mainly on the correlation between the weight of testis and the sex maturity． The 0.5g weight of testis was detcrmined as the landmarkof sex maturity． and according to the criteria．no adultmales were observed in Beijing area from January to February． In March and April，the population was mainly composed of group Ⅱ andⅢ， with most individuals being mature． From May to June，the population was composed of individuals of group Ⅲ and Ⅳ ，and all the individuals were sex mature ones. A small numbar of juveniles of group Ⅲ were making their first appearance from July to August．From September to October, the population was mainly composed of individuals be
longing to group Ⅱ andⅢ，and most of them reached Sex maturity，and atrophied were seen in group Ⅳ．In November and December， the population comprised four groups，and only a few individuals of group Ⅳ were seen with atrophied testes， while the three other groups were all immature． These results indicated that there were two peaks of the reproduction in May—June an July—August，and the latter was the main period of reproduction．and what is more．the males in the year generally did not reach maturity．
(2) The breeding characteristics of females： The studies covered the following aspects :1) The velocity of the sex maturity: In April months of 1983-1985，therewere 20.8— 54.1% fema1es entered the beginning of the breeding season， and the first young entered the population late after May，but most of them did not take part in
reproduction． The presence of embryo were noted only in few individuals in September and October． 2) Annual cycles of reproduction and the ecological Life-span：There were two pregnancy periods per year． and a part of the individuals were seen to te pregnant three times．The population renewed once a year fundam entally．The ecological Life-span maintained about one year. 3) The litter size varied annually with little fluctuation， it being 6.18±0.35 in 1982， 5.69±O.13 in 1983 and 5.97±0．20 in 1985．