臭鼩的繁殖和种群年龄结构

STUDIES ON REPRODUCTION AND POPULATION AGE STRUCTURE OF SUNCUS MURINUS

对浙江萧山瓜沥区农田臭鼩的研究,发现种群性比不等,存在明显的两性异型。分析了雄体的性成熟率和雌体的怀孕率及性活动率的变化规律。一年中存在两个繁殖高峰期。以齿长指数为指标,臭鼩种群可划分为4个年龄组。探讨了种群年龄结构的季节变化及其自然寿命。

A survey of the reproduction and pepulation age structure of the musk shrew (Suncus murinus) was conducted in Guali farmland area of Xiaoshan County, Zhe-jiang Province. In the population of the musk shrew, the sex ratio (males/females) was 1:0.72. The shrews showed a sexual dimorphism with the male being larger. The mean body weights of males and females were 54.9±1.13g and 37.9±0.70g and the mean body lengths of males and females were 122.9±1.10mm and 110.3±0.96mm re-spectively. The annual mean rate of sex maturity of males was 86.3%. 50% of males reached sex maturity when their testes weighed O.llg or their bodies 40g. All the males reached sex maturity at 0.13g testicle weight or 50g body weight. The pregnant fe-males were found nearly all the year round. 35.7% of the females caught were pregnant and 49.6% were stxually active. The average litter size was 3.5±0.16 ind.. Among the pregnant shrews, 25% were lactating. The females had two reproductive peaks in a year, occurring in Mar. -Apr. and July-Aug. respectively. Specimens of the musk shrews were divided into four age groups ty means of tooth length index which was based upon tooth wear. The seasonal changes in the population age structure are also discussed.