The gray fox is widely distributed in the San Gabriel Mountains,
occurring on both slopes of the range wherever extensive tracts of
chaparral are present. They reach maximum abundance in the chaparral
association of the coastal slope. Individuals have been observed
occasionally at night in coastal sage areas at the Pacific foot of the
mountains; however they seem to be less common here and probably come
out of the adjacent chaparral to forage in the flats at night. Gray
foxes occur all the way up the Pacific slope into the yellow pine
woodland at 7500 feet, and from 6200 feet elevation on the desert slope
down to the upper limit of the Joshua trees as, for example, near Mescal
Canyon at 4700 feet.
On the Pacific face of the mountains the gray fox probably is the
dominant carnivore in terms of its effect on prey species, first,
because of its abundance, and second, because of its forage habits. Some
appreciation of the abundance of the gray fox may be gained from
trapping records. On a fire road at the head of Thompson Canyon, at 2500
feet, two settings of traps about one-quarter mile apart were maintained
for four nights. In this time four gray foxes were trapped. At the head
of Cow Canyon, at 4500 feet, one trap set on a deer trail caught five
gray foxes in five nights. At the end of this time fox tracks were noted
about 100 yards away from the set, and another fox was trapped about one
quarter mile away. In addition to their abundance, the forage habits of
gray foxes are such as to bring them into most habitats present in the
chaparral association. Tracks and feces indicate that foxes forage under
dense brush, on open rocky ridges, in riparian growth, on talus slopes,
and in groves of big cone-spruce and scrub oak.
Trapped foxes, if uninjured by the trap, were usually released. One fox
was released on a small trail through thick vegetation consisting mainly
of snowbrush. When freed, the fox whirled and darted through a patch of
snowbrush for about seventy-five feet, then turned and disappeared
beneath some large bay trees. Although the brush through which it ran
was dense, the fox seemed to run at full speed. The success of gray
foxes as predators in the chaparral is probably due in large measure to
their agility amid dense cover.
The three specimens from the desert slope are referable to the coastal
subspecies, _U. c. californicus_, rather than the desert subspecies, _U.
c. scottii_. In all respects they resemble foxes taken on the Pacific
slope; cranial measurements are near the maximum for the large _U. c.
californicus_, and not small as would be expected if they were grading
toward the smaller _U. c. scottii_. Floors of desert valleys north of
the San Gabriel Mountains probably isolated foxes there from _U. c.
scottii_ found in the higher ranges of the Mojave Desert. Consequently
one would expect no intergradation between the coastal and desert races
in the San Gabriel Mountains.
An old female trapped on March 18,1951, in San Antonio Canyon, had three
embryos each about 105 mm. long from rump to crown, and weighed 9.2 lbs.
The average weight of four non-pregnant females was 6.8 lbs., whereas
the average of six males was 7.5 lbs.
_Specimens examined._--Total, 11, distributed as follows: Los
Angeles County: Mescal Canyon, 4800 ft., 1; 4 mi. E Valyermo,
5200 ft., 2; Cow Canyon, 4500 ft., 2; San Antonio Canyon, 3000
ft., 1; Thompson Canyon, 2500 ft., 2 (PC); 1/2 mi. W Palmer
Canyon, 2000 ft., 3 (PC).