In fall and winter, opossums devote almost twice as much time to feeding and improving their nests as they do the rest of the year. Opossums do not hibernate, but may den up during cold or snowy periods. Although they add a layer of fat, they do not grow a winter pelt, and their fur is poor insulation. Pennsylvania is near the species' northern limit, and many opossums lose the tips of their ears and tails to frostbite. Ticks, fleas, cestodes and nematodes parasitize opossums, and the species is preyed on by foxes, bobcats, hawks and owls.
Trappers also take some.
Many opossums are killed by vehicles while feeding on other highway-killed animals. The opossum is common in wooded areas throughout Pennsylvania. On a continental scale, it ranges from southeastern Canada south through New England to Florida, west to Minnesota, Nebraska and Texas, and south to middle America. It has been introduced in several western states. Opossums are unspecialized animals that can utilize a variety of foods and habitats.