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### 社鼠种群生态研究

1. 中国科学院动物研究所
• 出版日期:2006-07-29 发布日期:2007-09-13

### STUDIES 0N THE P0PULATION ECOLOGY OF SULPHUR BELLIED RAT

ZHANG Jie

• Online:2006-07-29 Published:2007-09-13

Abstract: In the period of 1983- 1986，the author had carried out the study on the population ecology of Sulphur Bellied Rat Rattus niviventer in Xishan area of Beijing。A totalnumber of 870( 464,406)rats were captured as samples．These sample rats were divided into five age groups according to their body weight excluding viscera ． Results showed that there were obvious seasonall disparities in age composition． The changes of the age composition were mainly caused by the changes of the reproductive behavior．Studies on the sex ratio represented that the proportion of female rats were generally higher than that of male in young and sub—adult groups．
The sulphur bellied rats started to breed from March to April， and most of them finished the breeding in September．Occasionally some individuals were found to be pregnant in October to December．The weight of the testis of the matured male rats were more than 0．8g．Females became matured at the age of 3— 8 months after being born， and usually started to breed only after overwintering．Most of females bred two foetus，but some of them bred once ，only a little individuals were found to breed three foetus in a year． The average of litter sizes for one foetus were 5.20． The number of litter sizes varied between 4．78—5．55．
The ecological life of sulphur bellied rat was 1．5 years or more．Some individuals participated breeding activities in two years．There were obvious seasonal difference in the number of population owing to the effect of reproduction and weather．The pattern of the changes in population was basically“S" type．The sulphur bellied rats inhabit onlv in mountain areas．They had not been found in plain．