Aquarium of the Pacific - Online Learning Center - Species Print Sheet
Conservation Status: Threatened
(Neotoma epida)Mammals • Terresterial
Woodrats are commonly called “pack rats” because they have a tendency to collect any curious object they find. The desert woodrat, Neotoma lepida, is one of 22 species of woodrats found in North and Central America. The smallest of southern California’s woodrats, it is related to cotton rats and deer, harvest, and grasshopper mice.
At the Aquarium
The desert woodrat is illustrated on the Wave’s mosaic tile mural, Rios de la Vida (Rivers of Life). The fountain, mural, and accompanying graphics illustrate the story of our Los Angeles and San Gabriel Rivers.
Great Basin, Sonoran and Mojave deserts from southern Oregon and Idaho, south through Nevada, western and southern Utah, southern and coastal California to Baja California, Mexico
These woodrats live in high desert areas, chaparral, sagebrush flats, pinyon-juniper pine, and desert trees such as catclaw and Joshua (yucca).
Woodrats have a compact body, lengthy long-haired tail, large ears, and large, slightly bulging, black eyes. Their feet are strongly built for grasping. Desert woodrats are a pale to dark gray washed with yellow above, light undersides, grayish to yellowish below, and gray at the base of the throat region. Hair bases are slate gray. Their tail, over half of the body length, is distinctively bicolored. Their hind feet are white.
Desert woodrats are 22-38 cm (9-15 in) long with a 9.5-18 cm (3.75-7.25 in) long tail. They weigh 109-136 gm (4-4.75 oz).
Desert woodrats usually feed at night and are primarily herbivores. In their desert habitats their diet consists of spiny cactus, yucca pods, creosote bush, cholla, pinyon nuts, seeds, prickly pear, and any available green vegetation. This species does not drink water; instead water is obtained from succulent, moisture-containing plants that are normal to the diet of these woodrats.
This species of woodrats has two to four litters per year, and sometimes five. After a gestation period of about 30 days, usually two to four blind, naked, and helpless young are born per litter. The young open their eyes at about 10 to 12 days of age. They nurse for 14 to 42 days depending on the size of the litter and the female’s health. The more young, the shorter the nursing period. They become sexually mature when about two months old.
Woodrats are commonly called “pack rats” because they have a tendency to collect any curious object they find, especially those that are small, bright, and shiny, and “pack” them back to their house or den. Should they find something more interesting, the first treasure is dropped to pick up the new one. Some objects are used in the construction of their houses to add strength and some are either deposited inside or at the entrance. Desert houses are often constructed in or around cactus with cholla and beavertail cactus pads and spines used in the construction plus the collected man-made debris. The entrance is often fortified with cactus spines. A nest is constructed inside the house. These shelters help to make the nest cooler in the hot summer and to retain the woodrat’s body heat in the desert’s cold winter. They also provide protection from most predators.
Desert woodrats are one of the few animals that can tolerate cactus spines. They are able to navigate between the spines without being harmed to get to the juicy pads.
Desert woodrats that live where there are creosote bushes are able to eat the toxic resin-containing leaves of the bush without ill effects because they can metabolically detoxify the resin and excrete the byproduct in their urine and feces. Researchers have shown that desert woodrats from other habitats do not have this ability.
Desert woodrats may live two years.
The U.S. Fish and Wildlife Service lists two woodrat species as endangered: the Key Largo woodrat, Neotoma floridana smalli and the riparian woodrat (Neotoma fuscipes riparia ). The latter is listed as a Species of Special Concern by California Fish and Game as is the San Diego desert woodrat (Neotoma lepida intermedia).
Desert woodrats are vulnerable to predation by coyotes, raccoons, owls, gopher and rattlesnakes, and hawks. Populations may be impacted by habitat loss to agricultural and urban development, isolation and fragmentation of habitats, and wildfires, especially in cactus areas. As estimated 30 percent of desert woodrat habitat was lost in the 2004 San Diego County wildfires.
Woodrats differ from “city” rats in that their tail is covered with hair which make the scales difficult to see; whereas, the tails of city rats are naked with very visible scales.