The Marin Humane Society

Opossums are marsupials. This means the female doesn't have a placenta and their young are born after a brief gestation period - about 11 days. For a litter to survive, the mother must carry them in her pouch for at least two months. In her pouch, the babies fasten themselves to a nipple and hold on for the entire two months. From the pouch the babies migrate to mom's back and there they are caried for most of their first year.

Mating season is from January to October, and it usually peaks from February to June. Opossums have between two and three litters a year. Litters average about eight young, but can be as many as 13.

Nocturnal, the opossum looks for food at night. These critters will eat just about anything. They are found on farmlands and woodlands, but have slowly migrated into more urban communities. They are quite common in any city block.

A mature opossum measures anywhere from 15 to 20 inches in length. Their tails alone can be as short as eight inches. Their bodies are covered, predominantly, with grayish-white fur, but the head is usually white. Both ears and tail are a fleshy, leather-like texture. Thick-bodied, short-legged, and a prominently pointed face, an opossum is fairly distinguishable. However, they are quite often mistaken for very large rats.

Because opossums are omnivorous and will eat any number of foods such as vegetables, fruits, nuts, meats, fish, eggs, insects, carrion, grains, and small mammals, they have been deemed scavengers. Thus, they raid garbage cans. Opossums, however, are pretty indiscreet about garbage can raids and are often caught red-handed. Keep opossums off the premises by:

Fencing in your backyard or garbage can area. If you catch one in the midst of a raid, don't corner it or attempt to pick it up. They have very bad tempers and 50 sharp teeth, so try to just frighten it away using lights or loud noise.
Pick up the family pet's food dish at night if you feed him/her outdoors. Opossums are not above a free domestic pet meal.
Securely fasten garbage can lids, and be sure to bag food scraps in plastic.
If you startle an opossum they may roll over on their side and play dead. If they do this, just leave them alone. They may lay there for an hour but eventually they will scurry away when it's safe.