山西省娄烦县北社鼠种群年龄结构及季节变动研究

Age structure and seasonal changes of Niviventer confucianus population in Loufan county of Shanxi province,China

目的对山西省娄烦县生态区2011年北社鼠种群年龄结构及季节变动进行研究。方法逐月捕鼠,将捕获的北社鼠鉴别雌雄并制作头骨标本,依据左侧第3上臼齿(M3)的生长与磨损程度鉴定北社鼠年龄后划分出该鼠各月的种群年龄组成。结果幼年鼠与亚成年鼠数量全年之和所占比例接近总种群的一半;成年鼠所占比例也较高,为43.13%;老年鼠所占比例最低,仅为7.81%;不同月份北社鼠种群年龄结构差异有统计学意义;成年组和老年组中雌性所占比例少于幼年组和亚成年组。结论北社鼠种群年龄结构月际更替关系明显,6-11月均有幼年鼠存在,繁殖期较长,成年雌性个体的生殖行为可能使其个体死亡率高于雄性,造成成年组和老年组中雌性比例下降。

Objective To study the age structure and seasonal changes of Niviventer confucianus population in Loufan ecological zone of Shanxi province, China, in 2011. Methods N. confucianus was caught monthly. The gender of the obtained N. confucianus was identified and then skull specimens were made. The ages of the obtained N. confucianus were examined according to the growth and wear degree of the upper left third molar （M3）. Then the monthly age composition of N. confucianus was determined. Results The yearly proportion of the juvenile and sub-aduh N. confucianus in the whole population was nearly 50%. The proportion of adult individuals was 43.13%; Old individuals accounted for only 7.81%, the least. N. confucianus showed significant differences in age composition between different months. The proportions of female individuals in adult and old age groups were less than those of juvenile and sub-adult groups. Conclusion Variation of age composition of N. confucianus in different seasons is obvious. Juvenile N. confucianus exists in each month between July and November and the breeding season is long. The reproductive behavior of adult females may make the mortality rate of females higher than the males＇, resulting in a declining proportion of female individuals in adult and old age groups.