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Wood rats, Neotoma spp., also referred to as “pack rats” or “trade rats”, are widely distributed over much of North America. One or more species are found in parts of most states with the exception of a few of the north-central and Great Lakes area states. They are also absent from most of the New England area. Some eight species and many subspecies are usually restricted to a given type of habitat, but members of this genus occur from low, hot, dry deserts to the cold, rocky slopes above timberline.
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. The common names, “pack” or “trade” rats, were giving these animals because of these antics. These characteristics are frequently the subject of exaggerated stories from which it is difficult to sift fact from fiction.
Wood rats are rat-sized mammals with large ears, large dark eyes and fairly long tail which is sparsely covered with hair or, depending on the species, well furred with long hair. Their fur is soft; dorsal fur is colored cinnamon, brown, gray, yellowish gray or creamy buff; feet and ventral parts are generally much lighter in color; the tail is blackish or puff, paler on the ventral surface. Wood rats are much larger than mice and tend to resemble the introduced Norway rat or roof rat in general size and shape. The head and body length is about 7 to 8 inches and the tail is 6-1/2 to 7-1/2 long. Their clean appearance, soft fur and well-haired ears help distinguish this native species from the Norway and roof rats.
Reproductive activity is most pronounced in spring. One to five litters a year are reported, with the number of young varying from one to four, with two about average. This species is not highly prolific and annual population increases or decreases are not great.
Wood rats have been involved in epizootics of plague and have been found infected with tularemia. They are reservoirs of the trypanosomes (parasitic, bloodinfesting protozoans) of Chagas’ disease. Their role in transmitting disease to man is considered minor, although dead or dying wood rats should not be handled with bare hands, especially in plague areas.
Some species such as the dusky-footed wood rat (Neotomafuscipes) are agile climbers and often construct bulky stick dens or nests high in the crowns of trees. More commonly, however, dens are situated on the ground. Ground dens measure 3 to 5 feet in height and diameter; tree nests are somewhat smaller. One animal may inhabit several nests, and in good feeding areas a den may be occupied for several years or a lifetime. Wood rats live alone except when mating or rearing young. The dusky-footed wood rat of the west is semiarboreal and, when traveling between tree nests, jumps squirrel-like from branch to branch. Other lowland and desert-living species are essentially ground dwellers.
Wood rats climb readily and are chiefly nocturnal; occasionally they are observed during daylight. Their food is largely determined by varying local conditions and consists mainly of a variety of green vegetation including grass, leaves, fruit, nuts, small bulbs, bark, dry seeds and fungi. They also may be attracted to human food supplies in buildings or in outdoor camps.
When wood rats nest in buildings, they may utilize available foods within the building, but most often they continue to feed outside. Visible ground trails 3 to 4 inches wide may be evident from the nest to the feeding grounds. In forest they clip young and debark older conifer trees for food and nest building, and in backyard or commercial orchards they will occasionally clip young 1/4-inch diameter limbs from fruit trees.
Girdling of small trees and shrubs occurs but is not common. Rarely do they become numerous enough to cause more than very limited damage to flower or backyard vegetable gardens. Nationwide they are considered a pest of very minor occurrence; however, locally they may be relatively significant pests.