Body Weight, Sex Ratio and Seasonal Reproductive Changes in the Indian Mole Rat, Bandicota bengalensis in the Punjab

Abstract

A study has been made of seasonal changes in the body weights of males and females, and of ovarian and uterine weights, in the Indian mole rat, Bandicota bengalensis, between July 1976 and June 1978, from areas surrounding Ludhiana (30°56'N.,75°52'E.). An attempt has been made to correlate them and peaks in reproductive activity with environmental factors such as daylength, temperature, rainfall and availability of food. During both years of study, the percentage of males was 45.2. The body, ovary and uterus were lighter during winter, and then gained weight, with peaks during April and August-September. Males were generally heavier than females. On the whole, 34.7% of females were either pregnant or lactating. The breeding season extended from mid-February to mid-October. Two peaks in breeding activity (April and August-September), with a decline during June, were separated by a period of reproductive inactivity from November to mid-February. The average litter size was 8.88 (range 5-13). Embryos occurred with almost the same frequency in the left and right uterine horns. The pre-implantation mortality was 9.6% and post-implantation mortality 4.8%; thus the total prenatal mortality was 13.7%. The percentage of embryos found resorbing was 4.1. The results have been discussed in the light of the literature on the reproductive biology of rodents in this region.