and summer, and give birth to litters of up to five young after a gestation period of 30 to 36 days. The young weigh about at birth, and are blind, with only the tips of their hairs visible. Their eyes open after about ten days. The teeth of newborn desert woodrats are initially splayed apart, creating a hexagonal opening between them, with which they clamp themselves to their mother's teats so firmly that they are difficult to separate. The teeth achieve their normal shape after about twelve days, but the young are not completely weaned until around four weeks of age. They live up to five years in captivity. Behavior Desert woodrats are primarily nocturnal and are aggressively solitary. They may defend water sources, such as succulent plants, against other species, and perhaps prevent other species from obtaining water during droughts. Desert woodrats sometimes appropriate the burrows of ground squirrels or kangaroo rats, and will fortify the entrance with several cubic metres of sticks and joints collected from jumping and teddy-bear chollas. This provides a formidable defense against predators. Living quarters are also often built against rock crevices, at the base of creosote or cactus plants, or in the lower branches of trees. Rock crevices appear preferred where available, but pack rats generally adapt to any situation. Woodrats construct houses for nesting, food caching, and predator escape. These can have up to six entrances and eight internal chambers, including both nests and food caches. Houses high and around across at the base are not unusual. Nests are constructed of dried vegetation, usually fibrous grass parts or shredded stems. Males mark their territory by rubbing themselves on the ground, depositing musky sebum secreted by large sebaceous glands on their abdomen. Females, however, scent mark by first digging, and then rubbing their flanks, legs or cheeks on the excavated soil. They are active year-round. References Desert woodrat Death-valley.us entry for desert woodrat Mammals of the United States Neotoma North American desert fauna Fauna of the Mojave Desert Fauna of the Sonoran Desert Mammals described in 1893 Taxa named by Oldfield Thomas