Although often described as “large rats”, opossums (Didelphis virginiana) are not rodents, but marsupials (relative of the kangaroo). They are the only marsupial in North America. Adult opossums are about the size of a cat and can weigh between four and fourteen pounds. Their fur ranges in color from white to dark grey. They have a pointed nose, small round ears, and a hairless tail that is prehensile. Their feet have five toes with the inside toe on the hind feet being opposable. Opossums were first introduced to California in San Jose in 1910. Opossums can do considerable damage to homes when looking for food or possible den areas. They may chew on electrical wiring, and tear at heating ducts, screened openings to attics and crawl spaces, and chew and claw at overhanging roof lines or decks to gain entrance. BIOLOGY Opossums can produce three litters per year, with 7 to 13 young per litter. They breed from January to November. The fetal young crawl to the female pouch 13 days after mating and attach themselves to teats. The young will remain in the pouch for seven to eight weeks. When the young emerge from the pouch they will move to the mothers back for approximately 4 months. When the young drop from the females back she does not retrieve them, thus they are weaned to start life on there own. Opossums are scavenging omnivores with a keen sense of smell. Pet food, fruit, vegetables, dead animals, garbage, and snails are common meals for urban opossums. They are not true predators, but will consume live food such as night roosting birds or poultry if the opportunity presents itself. Although they will occasionally eat mice or rats, they are not efficient predators of live rodents. Opossums will usually soil their nests with urine, feces and anal fluids resulting in offensive odors BEHAVIOR Opossums are usually nocturnal, although a steady supply of pet food can encourage them to come out in the daytime. Opossums will commonly live in attics, garages, woodpiles, and chimneys, or under houses, decks and hot tubs. Although, normally known to be solitary animals, it is not unusual for opossums to live in groups of different ages and sexes in urban areas where food is abundant. Pet food left in yards and fruit crops available year round in Santa Clara County eliminate the need to compete for food for survival, making life easy for opossums. Opossums are not aggressive and will not chase people or pets, but may hiss and growl if their food or den is threatened. Opossums have 50 teeth and will bite if handled. Opossums may also play “possum”; a behavior where they appear to be dead or in a trance like state when threatened. This behavior may also include baring teeth and hissing.