OPOSSUMS

Opossums are opportunistic omnivores with a very broad range of diet. Their unspecialized biology, flexible diet and reproductive strategy make them successful colonizers and survivors in unsettled times. Perhaps this is why their range has been expanding rapidly into North America.

Identification
An opossum (Didelphis virginiana) is a whitish or grayish mammal about the size of a house cat. Underfur is dense with sparse guard hairs. Its face is long and pointed, its ears rounded and hairless. Maximum length is 40 inches (102 cm); the ratlike tail is slightly less than half the total length. The tail may be unusually short in northern opossums due to loss by frostbite. Opossums may weigh as much as 14 pounds (6.3 kg); males average 6 to 7 pounds (2.7 to 3.2 kg) and females average 4 pounds (6.3 kg). The skull is usually 3 to 4 inches (8 to 10 cm) long and contains 50 teeth — more than are found in any other North American mammal. Canine teeth (fangs) are prominent. Tracks of both front and hind feet look as if they were made by little hands with widely spread fingers. They may be distinguished from raccoon tracks, in which hind prints appear to be made by little feet. The hind foot of an opossum looks like a distorted hand.

Range
Opossums are found in eastern, central, and west coast states. Since 1900 they have expanded their range northward in the eastern United States. They are absent from the Rockies, most western plains states, and parts of the northern United States.

Habitat
Habitats are diverse, ranging from arid to moist, wooded to open fields. Opossums prefer environments near streams or swamps. They take shelter in burrows of other animals, tree cavities, brush piles, and other cover. They sometimes den in attics and garages where they may make a messy nest.

Food Habits
Foods preferred by opossums are animal matter, mainly insects or carrion. Opossums also eat considerable amounts of vegetable matter, especially fruits and grains. Opossums living near people may visit compost piles, garbage cans, or food dishes intended for dogs, cats, and other pets.

General Biology, Reproduction, and Behavior
Opossums usually live alone, having a home range of 10 to 50 acres (4 to 20 ha). Young appear to roam randomly until they find a suitable home range. Usually they are active only at night. The mating season is January to July in warmer parts of the range but may start a month later and end a month earlier in northern areas. Opossums may raise 2, rarely 3, litters per year. The opossum is the only marsupial in North America. Like other marsupials, the blind, helpless young develop in a pouch. They are born 13 days after mating. The young, only 1/2 inch (1.3 cm) long, find their way into the female’s pouch where they each attach to one of 13 teats. An average of 7 young are born. They remain in the pouch for 7 to 8 weeks. The young remain with the mother another 6 to 7 weeks until weaned. Most young die during their first year. Those surviving until spring will breed in that first year. The maximum age in the wild is about 7 years.

Although opossums have a top running speed of only 7 miles per hour (11.3 km/hr), they are well equipped to escape enemies. They readily enter burrows and climb trees. When threatened, an opossum may bare its teeth, growl, hiss, bite, screech, and exude a smelly, greenish fluid from its anal glands. If these defenses are not successful, an opossum may play dead. When captured or surprised during daylight, opossums appear stupid and inhibited. They are surprisingly intelligent, however. They rank above dogs in some learning and discrimination tests.

Damage
Although opossums may be considered desirable as game animals, certain individuals may be a nuisance near homes where they may get into garbage, bird feeders, or pet food. They may also destroy poultry, game birds, and their nests.

Legal Status
Laws protecting opossums vary from state to state. Usually there are open seasons for hunting or trapping opossums. It is advisable to contact local wildlife authorities before removing nuisance animals.


Damage Prevention and Control Methods

Exclusion
Practical where opossums are entering structures.

Habitat Modification
Remove cover and plug burrows to reduce frequency of visits by opossums.

Frightening
Generally not practical.

Repellents
None are registered.

Toxicants
None are registered.

Fumigants
None are registered.

Trapping
Leghold traps. Box traps. Cage traps. Body-gripping (kill) traps.

Shooting
Effective where firearms are permitted. Use a shotgun with No. 6 shot or a .22-caliber rifle.




ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).