As the weather turns cold, you may see signs of opossums in buildings, looking for shelter. Opossums (Didelphis virginiana) have white to gray coloration in their fur, grow to the size of housecats, and weigh around 10 pounds. Their pointed faces and rat-like tails lead many people to consider them to be oversized rats. However, opossums are marsupials, not rodents.
Opossums live throughout most of Nebraska with populations greatest in the southeastern quarter of the state. Opossums mate twice a year beginning in mid-January through February and continuing into August. Litters average 8-10 young but can number as high as 17. Partially-developed opossums are born 13 days after mating, which then migrate to the female's pouch to continue to grow for several more weeks. At 6-8 weeks of age, the young leave the mother's pouch and begin to ride on her back. They are weaned at 3 months and disperse about 1 month later. Adult females mate again soon after the first litter is weaned. Young from the second litter are weaned and on their own by September or October. The young are capable of reproducing at 6 months of age, but usually don't until the year after they are born.
Opossums are omnivores with preferences for insects, carrion, and fruit. They favor rotten or well ripened fruit crops. Opossums will use available spaces and holes for dens rather than build their own. They are capable climbers but prefer to climb trees rather than structures. Winter weather is particularly hard on opossums as they frequently suffer frostbite to their tails and ears.
Opossums are valued for their meat and fur by Nebraska's hunters and trappers. Many enjoy watching them as they scurry through a backyard or seeing a footprint on a muddy stream bank. However, there are times when these species conflict with human interests.
Damage caused to landscaping is usually their digging, either under structures or for insects in the turf. The main concern related to livestock is a fungal disease that may develop if they defecate in hay that is fed to horses. Opossum generally will not harm pets or livestock as their primarily defense is to growl, hiss, show teeth, and then play dead.
Protect property by removing as many potential food sources as possible. Trash cans, preferably metal, should have tight fitting lids that remain attached even if tipped over. Questionable lids can be secured with bungee cords or wire. The best solution is to place trash containers inside secure sheds. Take care when putting food scraps in compost piles as this can be attractive to all forms of vertebrates.
Since opossums eat birdseed, hang birdfeeders on a wire between trees or on a baffled pole to prevent raiding. Reduce the amount of seed that falls to the ground by avoiding the use of mixed seed (use one type of seed per feeder) and using feeders that recapture fallen seed.