Wood rats are expert climbers but do not ordinarily go far up in trees. Both N. phenax and N. fuscipes, however, regularly nest and move about in trees. Several other species also sometimes build their houses in trees. Some populations that live near lakes and streams build their nests over water in mangrove trees, often 46-69 meters from the shore. The animals are not aquatic, however, and regularly forage on land.
Wood rats pick up material for their nests while foraging and carry it to the homesite.
If they find a more attractive substance, they will drop the material they are carrying and take the new item. They often select pieces of silverware or other shining objects from camps and leave the material they had been carrying. They do not drink much water, but during dry seasons they make heavy inroads on the fleshy stems of cacti and other plants that are well filled with water. Population density of N. lepida was listed as 1.2-6.1 per ha. There were on average 32 houses per ha.