Virginia Opossum (Didelphis virginiana)
Most people associate this mammal with the southern United States. Although native to the southeastern U.S., these marsupials have progressively moved northward and are now common through most of southern Ontario.
In Ontario, cold winters can be a limiting factor to expanding opossum populations but some have linked global warming with their northern expansion. This report supplies some basic information on the opossum and offers suggestions to help property owners reduce any possible conflicts with these animals.
Facts about the common opossum
• Adult opossums can reach 30.5 centimetres (12 inches) in height and about 81 centimetres (32 inches) in length including the 30.5 centimetre (12 inch) hairless tail. They can weigh between one kilogram and 5.4 kilograms (two and 12 pounds) and have light grey to black fur, black eyes, a pointed pink nose, pink feet and tail, and black ears.
• They are North America's only marsupial (female has a pouch) mammal. The female carries and nurses her young in this pouch until they are about two to three months old. For another month or two afterwards whenever they are away from the den they are carried on her back.
• Opossums may bear up to 14 young and when they are born the entire litter can fit onto a teaspoon. Like other marsupials, the blind, helpless young develop in a pouch. They are born 13 days after mating.
• Opossums are solitary and nocturnal, usually most active and looking for food at night. They are normally slow moving and therefore easy prey for a variety of larger predators. Their primary defence mechanism allows them to fall into an involuntary shock-like state which is widely known as "playing 'possum". In this state their lips are drawn back, teeth are bared, saliva foams around the mouth and a foul smelling fluid can also be excreted from their anal glands. While unconscious, people have even mistaken the animal as dead and carried it away for disposal.
• When upset or frightened opossums will hiss or growl and show their 50 sharp teeth but, in reality, they are usually gentle and timid.
• One reason that opossums can be so abundant in some areas is that they eat almost anything. As omnivores they eat insects, snails, rodents, berries, fruit, grasses, leaves, carrion, snakes, bird and waterfowl eggs, corn and all other vegetables.
• Another reason is their adaptability. They can live wherever water, food, and shelter exist. At home in trees, opossums use their prehensile tails to help stabilize themselves when climbing. They do not customarily hang by their tails as some folklore suggests.
• Opossums are typically nomadic, preferring to stay in an area as long as food and water is readily available. Although they will temporarily occupy burrows abandoned by other mammals, they do not dig out their own. They will seek out dark, secure areas either below or above ground.
• Females can have litters twice per year and usually give birth to five to eight baby opossums. Few live beyond 18 months in the wild, with rare reports of living five to 10 years in captivity. Opossums are killed by many predators, including humans (especially in cars), dogs, cats, hawks, owls and larger wildlife.
• When local populations of opossums are depleted, those remaining have been known to increase reproduction. Otherwise, it is not uncommon for other wildlife such as rats, skunks and raccoons to move in and occupy the area.
• Opossums are active year round and do not hibernate; however during extreme weather they may stay in dens for weeks at a time using up stored body fats. Home range can be two to three hectares (six to seven acres) but the area can be significantly smaller or larger depending on available food sources.
Human Conflicts with Opossums
Local peaks in opossum numbers occur throughout southern Ontario when food sources are high, shelter is abundant and predators are few. Therefore, in some instances opossums may create conflicts near homes where they may get into garbage, bird feeders, composters or pet food. In rural areas they may also destroy poultry, game birds, and their nests. Opossum proofing your residential or farm property may not be a sure thing, but the following steps will help.
• Do not leave pet food outside.
• Keep spilled bird feed cleaned up around feeders.
• Place bird food, such as beef suet, out of reach of opossums.
• Keep the lid on your composter and garbage cans tight with a bungee cord or strap.
• Keep the areas under decks, sheds and other buildings free from old lumber and other debris where opossums could find a suitable den.
• Prevent opossums from entering structures by closing openings to cages and pens that house poultry. Close off all vents or open spaces under buildings with metal, hardware wire, or boards. Be careful not to seal animals inside. If an animal is present, close off all of the area except for one small 30.5 cm x 30.5 cm (12 inches by 12 inches) opening. Wait until after dark, and then close it off. If the animal is still inside, repeat the process.
• Close garage, storage buildings, basement, and attic doors and windows, especially at night.
• Prune all large overhanging tree limbs that animals may use to gain access to a building roof or upper floor windows and vents. If trees cannot be pruned, tack a metal band, 41 to 61 centimetres (16 to 24 inches) wide, around the tree trunk below first limbs about 1.2 to 2.4 metres (four to eight feet) above the ground.
Respect wildlife from a distance. It has been reported that opossums are more resistant to rabies than other mammals such as skunks, bats or raccoons, however as with all mammals, they are still capable of being infected with rabies and other wildlife diseases.
Poisons cannot be used in Ontario by property owners to kill opossums or any other wildlife.
Live cage traps are effective when used in conjunction with habitat modification and removing possible food sources. Using fruit instead of meat as bait will reduce the chance of catching cats, dogs, raccoons or skunks. You can either humanely euthanize the opossum or release it within one kilometre from the capture site to minimize risk of spreading disease. If releasing the animal on private property, including municipal property, you must have the landowner's permission. Traps are available at some Rent-All shops or can be purchased from many hardware or Co-op stores. Use extreme caution when handling any wildlife and wear appropriate protective clothing such as leather gloves and boots.
Wildlife Removal Services
Under Ontario’s Fish and Wildlife Conservation Act, homeowners can remove wildlife in defence of livestock or property. Provincial or municipal government agencies are not responsible for removing nuisance wildlife on private property but can offer professional literature or advice. If property owners do not wish to remove animals that are damaging their property themselves they should contact one of many wildlife removal agencies found in the Yellow Pages of their local phone book, or they can obtain the phone number of a licensed trapper from their local MNR district office.
Finally, preventing opossums from creating problems on your property is ultimately the best long-term solution. Following the steps outlined here should help minimize the likelihood that opossums will cause problems or damage to your property. Conversely, some home owners have come to realize that the presence of an occasional opossum in their neighbourhood is not really a cause for great concern. Opossums have become established throughout southern Ontario and therefore seeing the occasional one here and there is to be expected.
For more information please contact the Ministry of Natural Resources' District Office that serves your area.