关键词: 小毛足鼠, 性比, 睾丸, 下降率, 怀孕率, 繁殖指数

Abstract:

【Abstract】　Objective　Study the breeding ecology of desert hamster（Phodopus roborovskii）. Methods　The population dynamics of P.roborovskii was investigated at different habitats in Ordos sand?land grassland in the middle ten days from April to October during 1991 to 1998 by rectilinear?trapping method. The trapped rodents were weighed, surveyed and dissected, and the breeding condition was recorded.  Results　Ten kinds of rodents were captured from 1991 to 1998. The desert hamster was one of dominant species, which accounted for 30.93% of all captured rodents. A total of 2562 desert hamsters were captured, including 1258 females with the proportion of (49.10±1.94)%. There was no significant difference in sex ratios with the change of seasons and years. The average decreasing rate of testicle in male was (70.55±2.47)%, and it began to decrease in February, ending in October. Average pregnant rate and placenta rate were (26.39±2.43)% and (21.38±2.27)%, respectively. The average number of fetal rats and placenta were (6.23±0.18) and (5.38±0.49), respectively. The females that produced two times each year accounted for (4.13±1.10)%. Average reproduction index was 1.062±0.162. The reproduction period of females was from March to November. The decreasing rate of testicle in scrotum, pregnant rate and reproduction index had obvious changes with seasons and years. Conclusion　There was significant difference among sex ratio, declining rate of testicle in scrotum, pregnant rate and fetal rats quantity of P.roborovskii with seasons and years.

Key words: Phodopus roborovskii, Sex ratio, Rate of testicle in scrotum, Pregnant rate, Reproduction index