The swift fox (Vulpes velox) is a small fox found in the western grasslands of North America, for example in Colorado, New Mexico and Texas. They also live in Saskatchewan and Alberta in Canada. Some mammalogists classify it as co specific with the Kit Fox, but many scientists have distinguished the latter from the swift fox. The reasons basically related to size. The kit fox is slightly larger than the swift fox, and the latter has a narrower snout.
Swift foxes weigh about 4.41 to 6.61lb (2 or 3 kg). They are primarily nocturnal, and are more heavily dependent on their dens than most North American canids. They suffer serious predation by coyotes.
Like most canids, the swift fox is an omnivore. Rabbits, mice, ground squirrels, birds and lizards are staples. Grasses and fruits round out their diet. However, like any efficient forager, the swift fox takes advantage of seasonal foods. During the summer, they eat large amounts of insects, including beetles and grasshoppers. Winterkilled deer and other carrion may also be important food sources.
Adult swift foxes live in pairs and may mate for most of their life. They may occupy up to thirteen dens in one year, moving because prey is scarce or because skin parasites build up inside the den. Sometimes they make other burrows from other animals bigger, even though they are completely capable of digging one on their own. Recent research has shown that social organization in the swift fox is unusual among canids, since it is based on the females. Females maintain territories at all times, but males emigrate if the resident female is killed or removed. This unusual structure may arise because the males have a smaller role than in many canids in bringing food to the young. It is rarely worth the effort to bring insect prey back to a summer den.