These rats were recorded from the yellow pine forests on Blue Ridge, at
8100 feet, down to the lower edge of the juniper belt, at 3800 feet.
Their presence there as elsewhere was determined by the occurrence of
adequate cover. On Blue Ridge they were taken in and near patches of
snowbrush, currant, and choke cherry, and one was taken beneath a pile
of logs where no nest was in evidence.
The thickets of choke cherry in hollows on Blue Ridge were favored
house-building sites of woodrats. Among the tangle of branches large
nests were built, and in September, 1951, the remains of choke cherry
fruit and gnawings on the limbs of these plants indicated that woodrats
were active throughout these extensive patches of brush.
In the pinyon-juniper association most of the large plants were used
as nesting sites, but scrub oak, seemed to be especially preferred.
Because it often grew in a twisted irregular form with the foliage
nearly reaching the ground, the oak offered good shelter for the woodrat
nests. In an acre of scrub oak and mountain mahogany brush one-half mile
north of Jackson Lake, at 6100 feet, thirteen occupied woodrat nests
were found. In the juniper belt, houses were of more irregular
occurrence, and were always beneath juniper trees, usually beneath the
largest and most widely spreading individuals.
Those specimens from Blue Ridge, on the crest of the San Gabriels, are
intergrades between the coastal race _macrotis_ and _simplex_ of the
desert slope. Although specimens vary widely in color, comparison with
series of these two subspecies in the California Museum of Vertebrate
Zoology indicates that all specimens from the desert slope of the San
Gabriels are referable to the race _simplex_. Two specimens of this
species from the granite talus above the base of Icehouse Canyon at 5500
feet on the Pacific slope, grade strongly toward _simplex_. Hooper
(1938:231) mentions that specimens of this species taken along the San
Gabriel and San Bernardino ranges may be intermediate between _simplex_
and _macrotis_.
At the head of Grandview Canyon, tracks indicated that a coyote had
foraged for about one half mile along the edge of a tract of dense oak
and pinyon growth. It seemed as if the animal had been foraging for
woodrats. A gray fox trapped near Graham Canyon, in the juniper belt,
had in its stomach the remains of a freshly killed adult woodrat. The
remains of an adult woodrat were found in the stomach of a rattlesnake
(_Crotalus viridis helleri_) obtained on the desert slope of the
mountains.
_Specimens examined._--Total, 6, distributed as follows: Los
Angeles County: 6 mi. E Valyermo, 5600 ft., 1; 1 mi. E Big
Pines, 6600 ft., 2; 1 mi. S and 3 mi. W Big Pines, 6000 ft., 1;
1 mi. S and 2 mi. E Big Pines, 8100 ft., 2.
=Microtus californicus sanctidiegi= R. Kellogg