A tail percentage of just over 80 is more typical of the interior valleys of California than of any forested part of Oregon and this situation emphasizes the effect upon small mammals which the pumiceous character of the soil and sparse vegetation seem to be producing.
| Ear Length | |||
| Class (in mm) | East Entrance | Dutton Ridge | Both |
| 15.5 | 1 | – | 1 |
| 16.0 | – | – | – |
| 16.5 | 2 | 1 | 3 |
| 17.0 | 1 | 5 | 6 |
| 17.5 | 1 | 1 | 2 |
| 18.0 | 1 | 2 | 3 |
| 18.5 | 1 | 1 | 2 |
| 7 | 10 | 17 | |
| Means: | 17.07 +/- .36 | 17.35 +/- .19 | 17.24 +/- .18 |
| Std. Dev.: | .95 +/- .25 | .60 +/ .13 | .77 +/- .14 |
The mean ear size of these mice is slightly below that of the Rim area, 17.5 +/- .09. Since the ear length is greater in larger mice the difference in body size between the Rim 90.09 +/- .38 and the eastern series may very well be the factor involved. The differences are not statistically significant.
Foot length: Since foot length must be computed separately in each sex that of the females in the combined East Entrance-Dutton Ridge series is the only one presented:
| Class (in mm) | Dutton Ridge-East Entrance |
| 19.0 | 2 |
| 19.5 | 2 |
| 20.0 | 3 |
| 20.5 | 3 |
| 21.0 | 1 |
| 11 | |
| Mean: | 20.0 +/- .19 |
| Std. Dev.: | .62 +/- .14 |
This mean is smaller than that of the Rim or South Entrance series both differences being statistically significant. For females the Rim foot length is 20.7 +/- .08 and South Entrance 20.6 +/- .15. Whether the difference in body size is the only factor is more doubtful in this case.
Summary
- Coues’ pocket mice were present and breeding along the East Entrance highway of Crater Lake National Park in 1941. These mice are at home in arid regions.
- Gambel’s deer mice taken from this region have a relative tail length typical of mice from the interior valleys of California.
- It is suggested that the sparsity of vegetation in this region is an important factor in these distributional arrangements.
