Pack rats are rat-sized mammals with large ears, large dark eyes and a relatively long tail. They are generally about the size of the common Norway rat. The head and body length is about 7 to 8 inches and the tail is 6-1/2 to 7-1/2 long. They are distinguishable from Norway rats by their hairy rather than scaly tail and their soft, fine fur and large ears. Their bodies are colored cinnamon, brown, gray, yellowish gray or creamy buff; generally their feet and bellies are generally much lighter in color. Their clean appearance, soft fur and well-haired ears help distinguish this species from the Norway and roof rats. Pack rats have long, sometimes bushy tails that is blackish or puff, and paler on the underside.

Wood rats are apparently attracted to small, bright, shiny objects such as spoons, small pieces of jewelry, broken bits of mirrors, coins or other items, sometimes leaving sticks, nuts or other materials in trade, giving them their common names, “pack” or “trade” rats. Woodrats climb readily and are usually active at night.