In this work are determined the productive periods and the number of fixed embryos/pregnancy in the species of non-flying small mammals in four different stages of regeneration of the Atlantic Forest in Silva Jardim and Casimiro de Abreu (Rio de Janeiro). Akodon cursor, Neclomys squamipes and Oryzomys nigripes showed repeated oestrus in all seasons. To A. cursor the average number in ten parturitions was of 3.6 youngs; in six parturitions N. squamipes and O. nigripes it was of 3.5 and 4.0 youngs, respectively. In these three species, the embryos fixed rather in the right horn of the uterus.
Rodentia; Cricetinae; Atlantic forest; ecology