REPRODUCTIVE CHARACTERISTICS OF 3 SYMPATRIC SPECIES OF MASTOMYS IN SENEGAL, AS OBSERVED IN THE FIELD AND IN CAPTIVITY

In Senegal, the occurrence of three sympatric species of the genus Mas tomys is now well established. Reproductive studies were undertaken on field samples from different biotopes and by laboratory breeding expe riments. For the three species the litter size at birth in captivity i s lower than the number of embryos recorded from pregnant females in t he field. The sex-ratio at birth and weaning is not different from 1/1 . The other reproductive characteristics can be summarized for each sp ecies as follows M. erythroleucus females, after a 21-day gestation pe riod, give birth to 7.1 individuals, 80 % of which survive to weaning. The mean interval between two successive litters is about 61 days. Fo r M. huberti females, the lengh of the gestation period is about 22 da ys. The mean litter size is about 6.4 and 72 % of newborn survive to w eaning. Sixty eight days separate two successive litters. M. natalensi s females, after a 21-day gestation period, produce about 6.5 young in dividuals every 53 days and only 50 % of them survive to weaning. It s eems that the larger distribution of M. erythroleucus, compared to the restricted distribution of the other species could be explained by it s greater reproductive performances that allow this species to coloniz e new habitats faster than the other ones.