It seems unlikely that competition for nesting sites between the two species of _Peromyscus_ affects the local distribution of each species. The analysis of nesting sites suggests that _P. truei_ is restricted, in Mesa Verde, by the availability of fallen logs, hollow branches, or hollow trunks of juniper trees. My observations lead me to think that within the pinyon-juniper woodland there is a surplus of nesting sites for individuals of _P. truei_. Many juniper trees have dead branches, and hollow juniper logs are abundant throughout the forest. It is inconceivable to me that the population of _P. truei_ could reach densities sufficient to saturate every nesting site available to them in the trapping grid. Sagebrush areas, or brushy zones adjacent to the pinyon-juniper woodland usually do not contain juniper logs; when hollow juniper trees or logs are not available, _P. truei_ is not found as resident of such areas. As mentioned earlier, individuals of _P. truei_ may venture into such areas to feed if they are adjacent to pinyon-juniper woodland. An individual of _P. truei_ may have more than one nest within its home range (for example Nos. 105 and 241 cited above). Each mouse probably has refuges, each containing a nest, strategically located in its home range. Thus, if a mouse is chased by a predator, or by another mouse, it need not return to its main nest, but can seek refuge in one of its secondary nests. These secondary nests were small and were invariably constructed from shredded juniper bark. Some of these nests were little more than a scant handful of shredded bark that formed a platform to sit upon. Other nests were larger and ball-shaped, with one opening on the side. All of the secondary nests that were found were inside hollow juniper logs. The bark used in construction of the nests had, in each case, been transported from nearby living trees. The logs had previously lost their bark through decay. The evidence indicates that these secondary refuges are prepared with considerable care. Not only is the bark transported for some distance, but it is shredded into a soft mass of fibers. When a mouse first establishes itself in a new area, perhaps it begins several such nests before settling upon the most favorable site. The less desirable sites, if still within the animal's range, are then available (barring competition by a new inhabitant) for outlying refuges. My data do not indicate whether individuals of _P. maniculatus_ use a similar arrangement of nests within their home ranges. The population of _P. maniculatus_ was sparse in the trapping grid, and the habitat these mice occupied was such as to make following them extremely difficult.