This mouse inhabits areas supporting chaparral on the coastal slope of
the San Gabriels below 5000 feet. In the chaparral it is usually the
most plentiful rodent, being dominant on slopes which have been burned
over and on which greasewood chaparral has taken over. On one such slope
at the head of Cow Canyon, at 4500 feet, this was the only rodent
trapped, although an occasional wood rat house was noted. Trapping
records gave the impression that this form was the most ubiquitous
rodent in the entire chaparral belt. Nearly every trap line, even in
such non-productive areas as oak woodland, took the California mouse;
and in many areas, as in thick lilac brush, this mouse was by far the
most abundant rodent. Specimens were taken on the damp ground next to
San Antonio Creek, and in the riparian growth. In San Antonio Wash the
California mouse was found in thickets of laurel sumac and lemonade
berry, or other large shrubs, but were absent from most of the adjacent
sageland. The one place where they were found away from heavy brush was
on a series of barren adobe banks, near Palmer Canyon, clothed mostly
with white sage. Here they found shelter in the unused burrows of
kangaroo rats and ground squirrels.
The only place on the desert slope where this species was taken was in
Mescal Wash. There it was taken occasionally near the large clumps of
antelope-brush and manzanita which grew in the main channels of the
wash.
Lactating females of this species were taken in October, 1949, and
February, 1950. Two pregnant females were trapped on February 25, 1950,
at the mouth of Palmer Canyon.
_Specimens examined._--Total 16, distributed as follows: Los
Angeles County: Mescal Wash (4200 ft., 4; 4300 ft., 1; 4500 ft.,
1), 6(2IM); San Antonio Canyon, 4500 ft., 1; San Antonio Canyon,
3000 ft., 5; mouth of Palmer Canyon, 1900 ft., 4 (PC).
=Peromyscus maniculatus gambeli= (Baird)