Animal Life in the Yosemite
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CALIFORNIA GRAY FOX. Urocyon cinereoargenteus californicus Mearns

Field characters.—Form and size suggestive of a small collie dog; tail bushy; head and body 22 to 27 inches (549-690 mm.), tail (without hairs at end) 13 to 16 inches (330-410 mm.), height of ear 2-3/4 to 3-1/8 inches (68-78mm.); weight 7 to 10 pounds (3.2-4.5 kilograms). Coloration of body and tail chiefly iron gray; stripe down middle of back and along tail to tip, black; breast, sides of body, and much of legs, rich yellowish brown; chin and middle of belly white. Voice: A sharp bark; captive individuals sometimes make growling sounds. Droppings: Doglike, but smaller, 1/2 inch in diameter.

Occurrence.—Common resident in Upper Sonoran and Transition zones on west slope of Sierra Nevada. Recorded from Pleasant Valley eastward to floor of Yosemite Valley. Lives chiefly in chaparral. Solitary.

The California Gray Fox is the predominant carnivorous mammal in the great tracts of chaparral which clothe the western flanks of the Sierra Nevada. While it ranges somewhat outside the brushland, it is as characteristic a member of the fauna there as is the wren-tit or the California Thrasher among birds.

Indications of the presence of Gray Foxes were observed at every camp which we made in the foothills. Tracks in the dust of roadways, droppings in the trails through the chaparral, accumulations of feathers in clearings where birds had been eaten, and even momentary glimpses of the foxes themselves, all testified to the abundance of the species. In fact we were led to suspect that the paucity of small mammals in certain places might be due in part to the relatively large numbers of Gray Foxes present. Estimates as to the actual population of foxes are difficult to make, but there must be, in favorable situations, at least two pairs to a square mile.

The Gray Fox is often active during the daytime; the members of our party saw at least three individuals at large during the midday hours. Two explanations may be suggested for this peculiarity of behavior: (1) In the chaparral a fox would usually be as well screened from view as though it were operating under cover of darkness. (2) At certain seasons vegetable materials predominate in the diet of this fox, and it is quite as easy to forage for such food during the daylight hours.

When moving about, a Gray Fox usually travels at a rapid trot, a gait which carries it over the ground with considerable speed, but without obvious effort. To judge from the tracks seen in some places, individuals do considerable scouting. In Yosemite Valley on the snowy day of December 10, 1914, the tracks of at least three foxes were observed between Mirror Lake and the foot of the Tenaya trail. They had covered a great deal of ground, mostly off the trail, going over and under boulders and through the brush thickets in their search for prey.

In general outline, the track of the Gray Fox resembles a dog's, but it is much smaller, being about an inch in each dimension. In the soft dust of roadways imprints of the claws are often made in addition to those of the four toes and the foot pad.

In silhouette the Gray Fox presents a slender body, relatively large ears, and a bushy tail, though that member is not quite so large proportionately as it is in the Red Fox. The presence of much steel-gray or iron-gray in the body coloration readily distinguishes the Gray Fox from the Red Fox, which is of similar general size but has larger ears, and from the coyote, which is much larger.

The most common note heard from the fox is a sharp bark, dog-like in character, and never prolonged like the wail of a coyote. A trapped fox sometimes makes growling sounds when a person approaches. It is probable that in the wild a fox gives voice just about as a dog would do under similar circumstances.

The Gray Fox is classed as a carnivore (flesh-eater) by reason of its structure and relationship, yet it partakes extensively of food that is vegetable in nature. During the fall and early winter months we saw many fox droppings along the trails which consisted largely and often exclusively of the hulls and seeds from manzanita berries (Arctostaphylos mariposa). These berries when ripe are notably sweet to the human taste and must be highly nutritious. This easily gotten food is also abundant and the berries are available over a long season, from the first of August to at least December. On the brushy slopes of the hills a fox would need to do much skilful hunting to get a sufficient supply of meat daily from cottontail rabbits, wood rats, mice and small birds; plenty of berries are to be had, however, simply for the eating. As to other vegetable food, we may note that in the stomach of a fox trapped at El Portal we found, among other items, some blades of grass; another stomach contained some finely chewed material which looked like oak-mast.

As to animal food, we are able to definitely report that one stomach contained the remains of a pocket gopher; another had claws of some carnivore (which, however, may have been used as bait for traps). One lot of droppings included ribs and vertebrae of a small rodent, probably a white-footed mouse. Local trappers told us that Gray Foxes would come readily to traps baited with 'cracklings,' even though this material was buried in the ground. The members of our field party used successfully, in addition to bacon scraps, the bodies of small birds and mammals whose skins had been removed for specimens. In only one instance were we able to affirm that a fox had devoured a quail. In Yosemite Valley on the morning of December 24, 1914, one trap in a setting put out for foxes contained the leg of a Mountain Quail. Beside the trap were fox droppings and quail feathers. The bird had accidentally gotten into the trap; then the fox had come along and feasted.

Foxes evidently prey upon small birds to some extent, though our evidence on this point is rather inferential in character. For example, while the senior author was walking along a road through the chaparral near Pleasant Valley, on May 25, 1915, there came to his ears, from a nearby cañon bottom, the reomonstrant chirping of a pair of Rufous-crowned Sparrows concerned over some marauder near their nest. A Bell Sparrow and a male Lazuli Bunting nearby lent voice to the demonstration. The observer approached cautiously and soon a Gray Fox was jumped in the ravine bottom. At Blacks Creek, near Coulterville, in May, 1919, a fox crossed the creek near our camp. At the instant the fox appeared a male Valley Quail, standing guard nearby, uttered a series of explosive sputtering notes indicative of great concern.

Judging from specimens obtained in the foothill country, the breeding season of the Gray Fox occurs in the spring months. No data were obtained locally as to the number of young, but elsewhere it has been ascertained to average four in a litter.


Animal Life in the Yosemite
©1924, University of California Press
Museum of Vertebrate Zoology

grinnell/mammals18.htm — 19-Jan-2006