Virginia Opossums (Didelphis virginiana) are present in Idaho and are now a regular part of the state’s wildlife population. They are the only marsupial found in North America, but they are not native to Idaho and are considered an exotic species. Their presence represents a northern and westward range expansion that has occurred over the last century. Opossums are nocturnal, adaptable animals often found near human settlements, making encounters common in certain parts of the state.
Status and History of Opossums in Idaho
The Virginia Opossum was historically confined to the southeastern United States. Their presence in the West resulted from both intentional and accidental introductions beginning in the early 1900s, with some sources suggesting they were released as a food source during the Great Depression. Since then, the species has steadily expanded its range across the continent.
This expansion into Idaho follows natural and human-modified corridors, primarily along major river systems. The opossum does not hibernate and is susceptible to frostbite on its hairless ears and tail during prolonged cold. Therefore, its distribution is often tied to areas of human development, which provide reliable food and shelter, mitigating the severity of the cold climate.
Where Opossums Are Found in Idaho
Opossum populations are not spread uniformly across Idaho; they are concentrated in areas offering favorable conditions. The highest density occurs in the southwestern corner of the state, particularly within the Treasure Valley. Cities like Boise, Nampa, Meridian, and Caldwell provide an ideal mix of water sources from the Boise River system, abundant cover, and readily available food resources in suburban environments.
Their distribution also extends into the lower regions of the Idaho Panhandle, including areas around Post Falls and Coeur d’Alene, where the climate is slightly milder. Opossums are habitat generalists but prefer riparian zones, agricultural lands near water, and urban environments. These areas provide opportunistic feeding grounds and numerous potential den sites, such as under sheds, decks, and in abandoned burrows.
Key Characteristics of the Virginia Opossum
The Virginia Opossum is easily recognizable as a cat-sized marsupial. They typically weigh between 4 and 13 pounds and are covered in coarse, grayish-brown fur, with a white face and black ears. A defining feature is their long, hairless, prehensile tail, which they use for balance and climbing. Adults are generally too heavy to hang by the tail for long periods.
Their hind feet feature an opposable, clawless thumb, which enhances their climbing ability. When threatened, the opossum employs its famous defense mechanism: an involuntary, shock-induced state of temporary paralysis known as “playing possum.” During this state, the animal appears limp, may drool, and can secrete a foul-smelling substance that deters predators.
Managing Encounters and Public Safety
Encounters with opossums are common in urban areas due to their opportunistic foraging. Despite a defensive hiss and an impressive display of 50 teeth when startled, opossums are generally non-aggressive and prefer to flee or feign death rather than confront a threat. A significant public safety point is their resistance to rabies; their naturally low body temperature (typically 94–97°F) creates an unfavorable environment for the rabies virus to survive.
To manage their presence around a home, reducing access to attractants is the most effective method.
Reducing Attractants
Securing garbage cans with tight-fitting lids, removing fallen fruit from the yard, and bringing pet food indoors before nightfall discourages foraging. If an opossum takes temporary residence in a structure like a shed or under a deck, exclusion techniques and removal of potential den materials are recommended. Local wildlife control professionals can be contacted if removal is necessary.