1936] 



MAMMALS OF OREGON 



175 



of the coast ranges. Their main distribution is in Upper Sonoran 

 Zone, and where found they usually accompany other species charac- 

 teristic of the zone. 



They are chaparral dwellers over much of their range, but also 

 enter the open forest and build their houses among the trees or even 

 in treetops. 



General habits. These are among the most noted of wood rat 

 builders, generally preferring their own structure to those of man, 

 or even to the strongholds of the rocks. Their houses are generally 

 in dense chaparral or in the underbrush of the woods, built up 

 around old logs, hollow trees, or many-stemmed clusters of rugged 

 shrubs. They are generally 4 or 5 feet high, as wide at the base, 

 conical, well formed, with 2 or 3 rooms aboveground and 1 below 

 the surface, aptly described as 2 or 3 stories and basement. The 

 houses are generally made 

 of sticks, twigs, bark, 

 chips, bones, leaves, and 

 moss, with strong, inter- 

 laced walls and supports, 

 in a peaked form that 

 will shed water and keep 

 the nests and food stores 

 dry and safe from most 

 enemies. Doorways lead 



under the houses and 



usually some doors and 



windows open out on the 



sides. The chambers are 



large enough for the 



well-formed, cup-shaped 



nests of soft moss and 



bark fibers and ample 



food stores conveniently near the nests. Runways, or well-worn trails, 



lead away from the houses to feeding grounds, to other houses, or to 



the base of trees, for these rats are great climbers and not only get 



much of their food from the treetops, but sometimes build large 



houses high up among the branches. 



They are active mainly at night, but if alarmed in the daytime 

 will run from house to house or climb trees and hide among the 

 leafy tops. They often visit barns or outbuildings, but rarely take 

 up their residence in them. Occasionally they carry away tools or 

 small objects for building material, but less commonly than do some 

 of the other species. The writer often missed his mousetraps and 

 found them on the nearest wood rat house. 



Breeding habits. Two to four embryos found in females taken 

 for specimens indicate small families, as do also the 4 mammae 

 arranged on 2 large glands in the inguinal region. Embryos noted 

 in February, March, April, May, June, and September indicate 

 much irregularity in the breeding season or more than one litter 

 a year. The animals are never numerous, however, and their increase 

 is evidently not rapid. 



. Food habits. While a large part of the food of these rats con- 

 sists of green vegetation, they also eat many fruits, nuts, and seeds, 



FIGURE 33. Range of the two round-tailed wood 

 rats in Oregon: 1, Neotoma fusoipes fusoipes; 2, 

 N. lepida nevadensis. 



