Annual reproductive patterns of female house shrew, Suncus murinus, in Taiwan

Reproductive patterns of female house shrew (Suncus murinus) inhabiting cen tral Taiwan were studied from September 1990 to February 1992 with animals collected monthly. The annual average body weight was 37.4 g for adults (N= 198), and 23.2 g for juveniles (N=18), respectively. The reproductive femal es (pregnant and lactating) were found all the year round with higher perce ntages (more than 80%) in spring-summer. The average litter size was 2.9 (r ange: 1-6). The levels of plasma estradiol-17 beta in adult females were hi gher in March-June (140 pg/ml), and decreased gradually to 98 pg/ml in Janu ary-February. Plasma levels of estradiol-17 beta in pregnant and lactating females were significantly greater than those of non-pregnant adults and of juveniles. Ovarian weights, plasma levels of estradiol-17 beta, and pregna ncy rate were correlated with day length. The pre-implantation mortality an d post-implantation mortality of the embryos were 6.9% and 1.6%, respective ly. The present study has demonstrated that the female S. murinus inhabitin g central Taiwan breeds all year round with higher reproductive activity in spring and summer.