Opossum (Didelphis virginianus)
The Virginia opossum is the only native member of the family Didelphidae and the sole marsupial found in North America. Opossums are sexually dimorphic with males generally larger than females. Opossums are well known for their tendency to carry young on their backs, after development in the marsupium.
Opossum abundance often varies greatly by habitat type and availability of den sites and densities have ranged from 1/4 acres to 1/50 acres. Generally, opossum populations follow a predictable annual cycle with lowest densities in winter and highest densities during early to late fall.
Because the opossum is a marsupial, it uses interesting breeding and reproductive strategies. Opossums have a short gestation period (<15 days) with most development of young occurring in the marsupium. Females are polyestrous and are capable of breeding multiple times if young are lost, but breed only once during each estrous cycle. Both sexes are capable of breeding within 6-8 months of age and opossums usually breed from December through February. Litter sizes range from 7 to 15 across the southeastern United States.
Opossums are omnivorous, eating a variety of prey such as small mammals, fruits, seeds, and insects. During periods of high fruit availability, opossums may prey almost exclusively on fruits, such as blackberries. Insects and their larvae are often selected during warm seasons. However, in early fall persimmons are often preferred by opossums and acorns are important during fall and winter.
Home range sizes may range from 10 to 365 ha and are larger for males, particularly during the breeding period. Opossums use a variety of habitats, including pine forests, bottomland hardwoods, mixed stands, marshlands, and grasslands.