The gray fox climbs bare tree trunks and sometimes dens high in trees
With hooked claws, the gray fox can scramble up a branchless trunk to 18 metres, leap between limbs and come down backwards like a house cat. It belongs to an ancient lineage that genetic studies place as sister to every other living canid, and its pupils are oval rather than slit-shaped.
Only two living species make up the genus Urocyon, Greek for tail dog: the gray fox and its dwarf cousin, the island fox of California's Channel Islands, which probably descends from semi-domesticated gray foxes that people ferried across. The species name cinereoargenteus means ashen silver, after the tail, which carries a black stripe ending in a black tip. Genetically the gray fox groups with two other old lineages, the raccoon dog of east Asia and Africa's bat-eared fox, rather than with red foxes. Fossils from Graham County, Arizona, show it in North America 3.6 million years ago, alongside giant sloths and early horses.
Adults measure 76 to 112.5 cm including the tail and usually weigh 3.6 to 7 kg. A gray fox can match a red fox's weight yet look smaller because of its shorter fur and legs, and it lacks the red fox's black stockings. Its range runs from southern Canada to Venezuela and Colombia, making it the only canid naturally found in both North and South America.
It was once the commonest fox in the eastern United States, until deforestation helped the red fox take over, but it remains dominant around the Great Lakes and the Pacific states and thrives in suburbs such as those of southern Florida. Coyotes and bobcats often kill gray foxes without eating them, a sign of competition rather than hunting, so the foxes stay near human activity, which the larger predators avoid, and travel and hunt along forest edges. In California they retreat into chaparral, where low shrubs offer escape.
Pairs are thought to be monogamous. Pregnancy lasts about 53 days and litters average 3.8 kits, which hunt with their parents at three months and forage alone by four. In one study of nine juveniles, young males roamed as far as 84 km while females stayed within 3 km of home. Gray foxes usually live six to ten years.
Source: Gray fox
