This mouse was recorded from 1900 feet elevation, one mile south of the
mouth of San Antonio Canyon, to 3200 feet elevation in Cajon Canyon.
This subspecies is characteristic of the sage belt and shows a strong
preference for the rough rocky areas found in dry washes. Although in
many areas the channels of the washes are immediately adjacent to sandy
sagebrush-covered flats, _eremicus_ is not common in the latter areas.
Rocks seem to be essential to _eremicus_, for sandy areas in the
sageland which were devoid of rocks yielded only an occasional specimen.
For example, 100 trap-nights in the main channel of San Antonio Wash
yielded 23 _eremicus_ and only six other rodents; while in the sandy
sage areas nearby 200 trap-nights yielded only one _eremicus_ and 32
other rodents.
In lower San Antonio Canyon _eremicus_ seemed restricted to the rocky
canyon bottom, none having been trapped on the steep slopes nearby. This
subspecies occurs commonly, however, on the adobe banks grown to white
sage at the base of the foothills. There _eremicus_ occurred on common
ground with _Perognathus fallax fallax_, and was often the only
_Peromyscus_ taken.
This species may be restricted by temperature; washes above 4000 feet
elevation, which seemed suitable were uninhabited by these mice.
On December 1, 1949, two females taken at the mouth of Palmer Canyon had
well advanced embryos. A female trapped in San Antonio Canyon on
September 19, 1951, was lactating. Juveniles were caught in the sage
belt in October, 1951.
_Specimens examined._--Total, 6, distributed as follows: Los
Angeles County: San Antonio Canyon, 2500 ft., 1; San Antonio
Wash, 1800 ft., 5 (PC).
=Peromyscus californicus insignis= Rhoads