Mammals of the San Gabriel Mountains of California Part 11

The spotted skunk usually was in rocky habitats. In the sage flats, sign (mostly feces and tracks) usually was near rock piles and around human developments such as rock walls, old outbuildings and houses. Specimens taken in the chaparral were trapped near granite outcroppings.

In the autumn of 1950, at my house near the mouth of Palmer Canyon, a family of spotted skunks lived under the floors. Night after night they scratched under the floor and chattered in high-pitched rasping notes, and on several evenings one walked complacently into the living room. It finally became necessary to trap and deport most of these skunks. In all, nine skunks were trapped; these probably represented more than the original residents. One male was descented and allowed to remain. It spent most of the daylight hours asleep in an old shower room where the many gaps between the rock work and the boards allowed him entrance.

Through no special efforts on our part he became tame enough to climb over us in order to get food left on the kitchen sink, and he would eat calmly while we sat only inches away from him.

Feces from sage areas contained mostly remains of insects and small rodents whereas many samples of feces from chaparral areas contained, in addition, sh.e.l.ls of snails. Feces examined represent all months of the year.

_Specimens examined._--Los Angeles County: mouth of San Antonio Canyon, 2 (PC).

Family CANIDAE

=Canis latrans ochropus= Eschscholtz

Coyote

Coyotes inhabit the sagebrush flats and foothills up to at least 4000 feet all along the Pacific base of the San Gabriels. This species seems most common at the foot of the range where large dry washes prevent man from occupying the land immediately adjacent to the foothills, and are the dominant carnivores of the coastal sage belt. Repeated observations have indicated that although many individuals range into the higher foothills they seldom are found deep in the major canyons or chaparral slopes. Coyotes rarely occur at 3000 or 4000 feet in San Antonio Canyon where it cuts into the realm of heavy chaparral; yet on steep foothill slopes and ridges, which are adjacent to the flat land, these animals range up to at least 4000 feet. Being hunters primarily of rather open land many coyotes go into the foothills only to find daytime refuge, traveling down dirt roads, ridges, and firebreaks, to forage at night in the sage flats. Coyote feces from the foothills, at about 3500 feet, contained predominantly the remains of such food items as cottontails, chickens, and jack rabbits. These animals could have been found only in the flats. This is additional evidence that coyotes do the major part of their hunting at the base of the range.

Observations of coyote tracks and trapping records have shown that these animals hunt mostly in the more open parts of the sage flats. Coyotes frequent areas of scattered brush, sandy areas, wash channels, and old roads, and seemingly shun dense brush. Many coyotes actually hunt for rabbits in the citrus groves near the foothills. On several evenings I traced their howling to orange groves, and Mr. Kenneth Hill of Upland told me of often seeing coyotes in his orange groves at night.

The forage beats of several coyotes were discovered in connection with trapping specimens of these animals. In January, 1952, two coyotes, probably a mated pair, traveled nightly from the slopes immediately west of Evey Canyon, at about 3100 feet, down into the sagebrush adjacent to the west side of San Antonio Wash, at about 1700 feet elevation. The route led down open ridges, then for about one half mile across a level, cultivated plateau, and then swung over the eroded banks near the lowermost point of the plateau onto the level sage flats. The distance covered by this route from the foothills down to the flats was somewhat more than a mile, with about a 1400 foot difference in elevation between the daytime retreat and the nocturnal forage area. Another route, seemingly used by only one coyote, was somewhat longer. This animal followed fire breaks and ridges from above Thompson Canyon down onto a fire road, and then into the lower end of Palmer Canyon where it entered the flats. This route covered about three miles in coming from the foothills to the flats. Feces of this coyote often contained the remains of white leghorn chickens which had been found at a refuse pile near several chicken ranches one-half mile from the base of Palmer Canyon.

Although no definite idea could be gained of the population density of coyotes in the area, it was clear that in certain localities they were, as carnivores go, abundant. After one large male was obtained in the flats at the base of Cobal Canyon, at least two other individuals were heard howling in this immediate area, and their tracks were noted repeatedly on dirt roads. One night early in January, 1952, immediately west of the head of San Antonio Wash, the voices of six coyotes could be picked out separately from a chorus of coyote howls which came from several different directions in the wash.

Many field examinations of coyote feces left the impression that chickens and lagomorphs made up the bulk of the coyote's food on the coastal slope. To check this a study of 39 sets of scats collected at various localities on the coastal slope was made in the laboratory, the results being shown in Table 10. Remains of one of the three species of rabbits, cottontails, jack rabbits, or brush rabbits, occurred in 72 per cent of the feces examined. Cottontails, it will be noted, were preyed upon more heavily than any other wild species, remains of this form being found in 33 per cent of the feces. The prevalence of chicken remains in coyote feces does not imply that these animals were killed by the coyotes. All of the chickens could have been found dead in the refuse piles of the many chicken ranches. In addition, the chickens were raised in wire cages above the ground where they were nearly invulnerable to predation. That coyotes may at times kill deer in this area was suggested by the finding of tracks in the sand in San Antonio Wash which clearly indicated that a deer had been closely pursued by a coyote. The tracks were lost in a stretch of brush so the outcome of the chase could not be determined. Near the mouth of Lytle Creek Canyon, in November, 1951, coyote feces contained mostly remains of grapes from nearby vineyards. Also, above Cucamonga, coyotes were found to be feeding heavily on grapes. This must be a rather unsuitable form of nourishment for coyotes, for many of the grapes in the feces appeared nearly unaltered despite their trip through the alimentary ca.n.a.l.

TABLE 10.--RESULTS OF EXAMINATIONS OF THIRTY-NINE SETS OF COYOTE FECES FROM THE PACIFIC SLOPE OF THE SAN GABRIEL MOUNTAINS. FECES WERE DEPOSITED IN AUTUMN AND WINTER (SEPTEMBER TO FEBRUARY).

=================================================================== | Number of | | sets of feces | Percentages Food item | which contained | of occurrence[A]

| food item | ------------------------------+-----------------+------------------ chicken | 18 | 46.2 ------------------------------+-----------------+------------------ Sylvilagus audubonii | 13 | 33.3 ------------------------------+-----------------+------------------ Lepus californicus | 10 | 25.6 ------------------------------+-----------------+------------------ Sylvilagus bachmani | 5 | 12.8 ------------------------------+-----------------+------------------ Odocoileus hemionus | 5 | 12.8 ------------------------------+-----------------+------------------ rodents (unidentified) | 5 | 12.8 ------------------------------+-----------------+------------------ Dipodomys agilis | 4 | 10.3 ------------------------------+-----------------+------------------ Neotoma species | 3 | 7.7 ------------------------------+-----------------+------------------ Mephitis mephitis | 3 | 7.7 ------------------------------+-----------------+------------------ Carrion beetle | 2 | 5.1 ------------------------------+-----------------+------------------ pa.s.serine bird | 1 | 2.67 ------------------------------+-----------------+------------------ bot fly larva | 1 | 2.67 ------------------------------+-----------------+------------------ snail sh.e.l.l | 1 | 2.67 ------------------------------+-----------------+------------------ scorpion | 1 | 2.67 ------------------------------+-----------------+------------------ Jerusalem cricket | 1 | 2.67 ------------------------------+-----------------+------------------ sheep hair | 1 | 2.67 ------------------------------+-----------------+------------------ Lynx rufus | 1 | 2.67 ------------------------------+-----------------+------------------ Kitten of wildcat or housecat | 1 | 2.67 ------------------------------+-----------------+------------------ Lophortyx californica | 1 | 2.67 ------------------------------+-----------------+------------------ grapes | 1 | 2.67 ------------------------------+-----------------+------------------ gra.s.s | 1 | 2.67 ------------------------------+-----------------+------------------

[Footnote A: This is an expression, in percentage, of the number of sets of feces which contained the particular food item out of the total of thirty-nine sets examined.]

The six coyotes taken on the Pacific slope are fairly uniform in coloration; the occurrence of white tipping on the tails of most of the specimens, instead of the usual solid black tip, is notable. Three skins, those of a male and two females, have patches of white hairs at the tips of the tails; two skins, of a male and a female, show only scattered white hairs at the tips of the tails; and the skin of one female has a solidly black-tipped tail. An additional female, trapped by David Leighton in Thompson Canyon, had a large patch of white hairs at the tip of the tail. Grinnell, Dixon, and Linsdale (1937:501) mention that only an occasional individual (female?) has a white-tipped tail.

Weights are available for four specimens: two coyotes trapped in San Antonio Wash, a male and a female, weighed 20.5 and 23.2 pounds respectively; a female from the mouth of San Antonio Canyon weighed 21.6 pounds; and a large male from the mouth of Thompson Canyon weighed 29.3 pounds.

_Specimens examined._--Total, 6, distributed as follows: Los Angeles County: Live Oak Canyon, 3000 ft., 1; mouth of San Antonio Canyon, 2000 ft., 1; 4 mi. N Claremont, 1600 ft., 2; 4 mi. NE Claremont, 1600 ft., 1; 3 mi. NE Claremont, 1600 ft., 1.

TABLE 11.--CRANIAL MEASUREMENTS OF CANIS LATRANS OCHROPUS FROM THE COASTAL SLOPE OF THE SAN GABRIEL MOUNTAINS.

====================================================================== | Four females | Two males | Averages Extremes | Averages Extremes ----------------------+-----------------------+----------------------- Condylobasal length | 180.67 174.2-183.3 | 188.35 179.2-197.5 ----------------------+-----------------------+----------------------- Palatal length | 91.57 88.0-95.0 | 97.15 91.6-102.7 ----------------------+-----------------------+----------------------- Zygomatic breadth | 90.15 88.9-92.0 | 95.60 88.8-102.5 ----------------------+-----------------------+----------------------- Interorbital breadth | 29.12 27.9-29.9 | 31.45 28.1-34.8 ----------------------+-----------------------+----------------------- Length of | | maxillary toothrow | 85.00 80.4-89.80 | 88.00 83.4-92.6 ----------------------+-----------------------+----------------------- Length of | | upper carna.s.sial | 18.30 17.8-19.0 | 18.70 18.1-19.3 ----------------------+-----------------------+-----------------------

=Canis latrans mearnsi= Merriam

Coyote

Coyotes are common on the desert slope of the San Gabriels below about 6000 feet elevation. They seem not, or only rarely, to penetrate the yellow pine forest belt, but tracks have been found occasionally near the lower edge of the forest, as at the head of Mescal Canyon. In the more open parts of the pinyon-juniper a.s.sociation, sign of coyotes was noted and they were the dominant carnivores in the juniper belt and Joshua tree woodland.

In the upper part of the pinyon-juniper a.s.sociation coyotes travel and forage in sage flats, along ridges, and in sandy draws, avoiding the extensive patches of scrub oak and mountain mahogany, and the steep, rocky, pinyon-covered slopes. It is apparent that the local ranges of the coyote and the gray fox in the pinyon-juniper belt are complementary, the gray fox keeping to the more thickly wooded or brushy parts of the area, and the coyote staying in the relatively open sections. Probably there is little compet.i.tion for food there between these two canids.

As evidenced by tracks, coyotes commonly traveled and hunted along desert washes, probably because of the larger population of rodents and rabbits there. Below Graham Canyon three fairly recently inhabited dens of coyotes were found in the cutbanks at the edge of a dry wash in December of 1951. The cutbanks were six to ten feet high, and the dens were dug into the banks about three feet above the floor of the wash.

On the evening of October 20, 1948, near Desert Springs, Steven M.

Jacobs and I set out a line of fifty wooden live traps for kangaroo rats. That night we slept about 300 yards from the middle of the line which was roughly three quarters of a mile long. When we tended the traps the next morning we found the tracks of a coyote over our own tracks of the previous day, and the first trap that had seemingly held a kangaroo rat was chewed and dragged for about fifty feet. Each trap that had held a rodent had been turned upside down so that the door had opened. At one point in the line where we had walked for about two hundred yards without setting a trap the coyote had followed every twist and turn of our trail. The animal had followed out the entire trap line and removed approximately eight rodents from the traps, reducing our take to one _Dipodomys_ and one _Peromyscus_.

Examinations of feces showed that in the period from 1948 to 1952, while populations of jack rabbits were low in the Mojave Desert, the coyotes had fed extensively on smaller mammals such as kangaroo rats, and to some extent on fruit. By contrasting the present food habits of coyotes on the desert and coastal slopes of the mountains support is afforded for Errington's (1937:243) statement that predation is "a by-product of population." On the desert slope, with low populations of rabbits, the coyotes have turned to lesser species of prey; while on the Pacific slope, where populations of rabbits were high, the rabbits made up the major portion of the coyote's diet. On the desert slope, remains of the following food items were identified from coyote feces: kangaroo rats, mule deer, jack rabbits, pa.s.serine bird, manzanita and juniper fruit, beetles, grapes and apples. Near Valyermo, coyote feces were composed mostly of apples from nearby orchards. A female coyote killed below Grandview Canyon had its stomach and intestines stuffed with apples in large chunks. In the juniper belt, berries of juniper were often eaten by coyotes.

The three specimens of coyotes from the desert slope are clearly referable to the desert race _C. l. mearnsi_, both with regard to cranial and pelage characteristics. Although I collected no specimens from Cajon Pa.s.s or the pa.s.ses at the west end of the range, it is in these places that intergradation might be expected to occur between the desert race _C. l. mearnsi_ and the coastal and valley subspecies _C. l.

ochropus_, as the higher parts of the San Gabriels seem to const.i.tute a barrier to coyotes.

A subadult female coyote taken in the Joshua tree belt near Graham Canyon weighed 20.8 pounds.

_Specimens examined._--Los Angeles County: 6 mi. E and 2 mi. S Llano, 3600 ft., 3 (2 PC).

=Vulpes macrotis arsipus= Elliot

Kit Fox

The kit fox barely enters the area under consideration. In the Joshua tree belt, below about 3500 feet elevation, tracks were most often noted in washes and on the adjacent sandy ground. The highest place where tracks were seen was a small sandy draw below the mouth of Graham Canyon at an alt.i.tude of roughly 3900 feet.

In the Joshua tree belt many old burrows were found but none was occupied. I believe these foxes are returning to this area where once they were common. In the winter of 1948 no sign of kit foxes was found, although intensive field work was done in the Joshua tree belt in the Mescal Canyon area. In December of 1951, in the same locality, sign was obvious and an individual was trapped below Grandview Canyon at 3500 feet elevation. Possibly since the use of poison for carnivores has been discontinued in this district the foxes are repopulating the area.

The one specimen taken, a sub-adult female, weighed two pounds and fourteen ounces.

_Specimen examined._--Los Angeles Co.: 6 mi. E & 1 mi. S Llano, 3500 ft., 1.

=Urocyon cinereoargenteus californicus= Mearns

Gray Fox

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 a.s.sociation 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 a.s.sociation. 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 s...o...b..ush. When freed, the fox whirled and darted through a patch of s...o...b..ush 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).