Name: Pack rat, also called a trade rat or wood rat.Size: They range in length from 8 to 20 inches, including their 3- to 9-inch tail.Food: A diet of spiny cactus, yucca pods, bark, berries, pinyon nuts, seeds and any available green vegetation. They rely on succulent plants for their water.Habitat: Pack rats are prevalent in the deserts and highlands of western United States. Pack rats build complex nests of twigs, called "middens", often incorporating cactus. Nests are often built in small caves, but frequently also in the attics and walls of houses. Some will use the base of a prickly pear or cholla cactus as the site for their home, utilizing the cactus' spines for protection from predators. Others, like the burrows of ground squirrels or kangaroo rats and fortify the entrance with sticks and bits of spiny cactus stems fallen from Jumping and Teddy-bear Chollas.Behavior: Pack rats are active nocturnally (at night).They are especially fond of small, bright, shiny objects which they will readily confiscate.In fact, while carrying one trophy, the rat may see another that is more attractive, and so puts down the first to pick up the second, since it can carry only one item at a time.Woodrats can become quite a nuisance, getting into everything from attics to car engines, stealing their treasures, damaging electrical wiring and wreaking general, noisy havoc. The reproductive habits of rodents are extremely variable. They have been known to deliver up to 5 litters per year with as many as 5 young per litter. ( That's 25 new rats a year per female, Wow!!! ) Name: Roof rat or Black rat.Size: A typical rat will be 15–20 cm (5.9–7.9 in) long with a further 20 cm (7.9 in) of tail. In fact, it is distinguished from other rats by that tail, which is longer than the rest of its body.Food: They have a preference for grains,fruits, and nuts. They are also a frequent predator of small birds, seeds, invertebrates, and perhaps lizardsHabitat: Outside, roof rats will nest in