In general, the two species tended to be restricted to certain areas of the trapping grid where the respective habitats were more favorable for their needs. Figure 4 shows the parts of the trapping grid utilized by each species. Of course there is overlap in the areas utilized by each species; a few individuals of _P. maniculatus_ may be found in what appears to be _P. truei_ habitat, and _vice versa_. In such cases, an inspection of the vegetation usually reveals an intermediate type of habitat--for example, an open sagebrush area in pinyon-juniper woodland--that is habitable for either or both species. The ranges of _P. truei_ tend to be clustered in the western half of the trapping grid, whereas the ranges of _P. maniculatus_ are clustered in the eastern half of the grid (Fig. 4). The vegetation of the grid and the preferred habitats of each species are discussed in following chapters. On the basis of the sizes of estimated home ranges, it is possible to compute the approximate number of individuals of each species that occur in each acre of appropriate habitat. [Illustration: FIG. 4: Diagram of trapping grid south of Far View Ruins, showing the preferred habitats of _P. truei_ and _P. maniculatus_.] On the basis of an average home range of 30,206 ± 25,545 square feet (one standard deviation) for both male and female individuals of _P. truei_, there should be approximately 0.781 to 9.345 individuals of this species per acre of pinyon-juniper woodland. An average home range of 29,400 ± 24,570 square feet for males and females of _P. maniculatus_ indicates that the density of this species is between 0.807 and 9.018 animals per acre in mixed shrub or shrub and sagebrush types of vegetation. Figure 4 shows that approximately 10 of the 16 units of the trapping grid are suitable habitat for _P. truei_; the remaining six units are habitat of _P. maniculatus_. From the preceding calculations of density one could expect to find between seven and 90 individuals of _P. truei_, and between five and 54 individuals of _P. maniculatus_ as residents within the 22.95 acres of the trapping grid. The higher estimates of density appear to be large enough to compensate for any overlapping of home ranges. The calculation of density of each species within the trapping grid is dependent upon the precision with which the home ranges of individuals can be estimated. At this time, home ranges of small rodents can not be measured with great precision, therefore any such calculations are, at best, only approximations. This does not imply that estimations of home range are of little value; however, calculations of density, using home ranges as a basis, tend to amplify the variance inherent in the data. This amplification is reflected in the wide range between low and high limits of the densities for each species within the trapping grid.