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  The Mammals of Texas - Online Edition

Swift or Kit Fox
Order Carnivora : Family Canidae : Vulpes velox (Say)

Swift or Kit Fox (Vulpes velox).  Photo by John L. Tveten.Description. Smallest of the American foxes; upperparts pale buffy yellow, frosted with white and lightly washed with blackish; back of ears yellowish brown; tail buffy gray with black tip and black spot at base on upperside; underparts whitish. Dental formula: I 3/3, C 1/1, Pm 4/4, M 2/3 x 2 = 42. External measurements average: total length, 840 mm; tail, 330 mm; hind foot, 135 mm; ear, 75 mm. Weight, 1-3 kg.

Species distribution mapDistribution in Texas. Known from western one-third of state east to Menard County.

Habits. These small foxes, not much larger than a good-sized house cat, generally live in the open desert or grasslands where they often have dens and hunt mesa country along the borders of valleys, sparsely vegetated habitats on sloping plains, hilltops, and other well-drained areas. Also, they have adapted to pasture, plowed fields, and fencerows. They rely on speed and nearness to their dens for safety.

Swift or kit foxes are primarily nocturnal, although they may occasionally be seen in the daylight hours. Usually, they emerge from their dens shortly after sunset for hunting, which occurs sporadically throughout the night. Foxes may cover several kilometers while systematically hunting for prey but seldom venture more than 3 km from their dens. Home ranges may overlap broadly, and foxes from different family groups hunt the same areas, although not at the same time.

The diet of these foxes consists largely of small mammals, particularly rodents, but also includes insects, small passerine birds, lizards, amphibians, and fish. Known food items are kangaroo rats, jackrabbits, cottontails, small birds, grasshoppers, Jerusalem crickets, and other insects. W. L. Cutter examined 12 stomachs and 250 scats (droppings), collected mainly in late spring, summer and early fall, to determine the food habits of these foxes. Rabbit remains, both cottontails and jackrabbits, were found almost as frequently (60 times) as all other vertebrates combined (68 times). Small rodents occurred 26 times; passerine birds, 33 times; lizards, four times; and fish, three times.

No remains of gallinaceous birds, either game birds or poultry, were found although two of the dens were no more than 170 m from a farmyard where poultry was raised. Insect remains (11 families represented) comprised approximately 29% of the bulk of the stomach contents and 55% of the bulk of the scats. Shorthorned grasshoppers occurred most frequently, followed by beetles of three families. Grass was found in 43 scats and 10 stomachs. Thus, it appears that this fox is not in conflict with man’s interests insofar as its feeding habits are concerned.

Male and female foxes establish pair bonds during October and November, during which time large family dens are used. These foxes are monogamous for a breeding season but the pairs are not necessarily the same from year to year. Breeding occurs from December to February, and most litters are born in March or early April. Litter size varies from three to six and the swift or kit fox is monestrous. W. L. Cutter observed that in the Texas Panhandle (Hansford County) these foxes usually den in open, overgrazed pastures. Of 25 occupied dens that he observed, 19 were so located; two were in plowed fields and four were along north-south fence rows. The den is a simple structure with one or more openings. One that Cutter excavated had a circular entrance 20 cm in diameter and a total of 378 cm of open, underground tunnel. The main chamber was 30 cm wide, 22 cm high, and 80 cm below the surface of the ground. Three dens were as close as 85 m to human habitation. These foxes spend most of the daytime in their dens; when they do come out in daylight, they remain close to the den into which they retreat when molested.

Swift foxes are relatively unafraid of man and are far less cunning than most other foxes. They are so unsuspicious that they are easily trapped, and even more easily poisoned. Consequently, wherever trappers are active, and especially wherever control campaigns involving the use of poison have been carried out against predatory animals on areas inhabited by swift foxes, the foxes have been greatly reduced in number or entirely eliminated.

Remarks. In previous editions, arid-land foxes have been regarded as comprising two similar but separate species, the swift fox (Vulpes velox) and the kit fox (Vulpes macrotis). However, in a recent taxonomic study of these foxes using advanced morphometric and protein-electrophoretic methods, Dragoo and colleagues concluded that these taxa are not sufficiently distinct to warrant separate specific status. Thus, the two foxes are now grouped into a single species, Vulpes velox, comprised of two subspecies, V. v. velox and V. v. macrotis.

Photo credit: John L. Tveten.