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. Some mammalogists classify it as conspecific with the Kit Fox V. microtus, but molecular systematics imply that the two species are distinct.

Swift Foxes weigh about 2 or 3 kg. At least during the summer, they eat mainly insects. They are primarily nocturnal, and are more heavily dependent on their dens than most North American canids. They suffer serious predation by coyotes.

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 less of role than in many canids in bringing food to the young, because it is rarely worth the effort to bring insect prey back to a den.

Reference

• Kamler, J. F., Ballard, W. B., Gese, E. M., Harrison, R. L., Karki, S., & Mote, (2004). Adult male emigration and a female-based social organization in swift foxes, Vulpes velox. Animal Behaviour, 67, 699-702.