REPRODUCTION IN THE WHITE EARED OPOSSUM (DIDELPHIS-ALBIVENTRIS) UNDERTEMPERATE CONDITIONS IN ARGENTINA

The reproductive cycle of the white eared opossum Didelphis albiventri s Lund was studied in an area of temperate climate conditions in the r egion of Buenos Aires Province, Argentina. In 1987-1988 and 1988-1989 the reproductive season began in late August and continued until mid-M arch. Two distinct breeding periods per season were evident, the first in early September and a second in December. Litter size ranged from 4 to 9. The sex ratio in the pouch was 1:1. Only those females that ga ve birth early in the season could produce a second litter in December . Progressive pouch mortality was not found. Young opossums were weane d at 3.5 months of age and remained sexually inactive until the next r eproductive season. Ages of captured opossums suggest that few animals survive for more than 20 months. Therefore, in the study area, most s pecimens breed only during one reproductive season. In South America, a latitudinal dine in the timing of the breeding season extends from t ropical to temperate areas.