opossums

Opossums

by Andrea Johnson

Opossums (Didelphis virginiana) are the only marsupials native to the United States and the Virginia opossum is the only opossum found in Oregon. Named for the state where the first specimen was described, Virginia opossums are native to the eastern and southern regions of the United States.

The first opossums in Oregon arrived as pets around 1910. Some of these pet opossums escaped or were released, establishing permanent populations in Oregon. The opossum has unique characteristics that make it an interesting animal to study and rehabilitate. The Virginia opossum is a cat-sized mammal (25-40 inches long, 8-13 pounds). It has short black and white underfur covered by white, coarse guard hair.

The coloring is white around the face and mottled white and black around the body and legs. The ears and part of the tail are mostly hairless and black. The opossum is a good climber, having five toes on each foot including thumbs and big toes which are opposable and allow grasping of branches.

Opossums have 50 teeth—more than any other mammal in North America. Since they are marsupials, opossums have pouches in which the young spend most of their time during development. Opossums are solitary, only living in groups when a mother is raising her young. Opossums are generally nocturnal, but may venture out during the day in winter.

Opossums are opportunistic feeders, eating what is available. Foods include insects, slugs, berries and other fruit, frogs, small mammals, carrion, pet food, and scraps from household garbage cans. Oregon's opossums are restricted to the west side of the state where the environment is most suitable.

Opossums prefer to live in forests where their dens can be in close proximity to a water source such as a stream or pond. Opossum dens are commonly made from abandoned burrows of other animals, in hollow trees, brush or rock piles, or under buildings.

Perhaps the most popular (and curious) behavioral trait of the opossum is its defense mechanism of "playing dead." When threatened, the opossum will fall on its side and remain almost completely still, drool, and emit a foul smelling odor from its anal glands. The opossum can remain in this position for hours until it determines that the threat has disappeared.

Opossums have up to two litters of young per year, though it is not agreed upon how many babies are usually born in each litter, the range is from 5-22. The babies develop inside the mother for about 12 days, and are born naked and helpless, with only enough instinct and ability to drag their way towards the pouch and attach to one of the 13 teats inside. The successful babies will remain attached to the teats, continually nursing, for approximately 60 days.