|Corsac fox range|
The corsac fox (Vulpes corsac), also known simply as a corsac, is a medium-sized fox found in steppes, semi-deserts and deserts in Central Asia, ranging into Mongolia and northeastern China. Since 2004, it has been classified as least concern by IUCN, as populations fluctuate significantly, and numbers can drop tenfold[clarification needed] within a single year.
It is also known as the steppe fox, and sometimes referred to as the "sand fox", but this terminology is confusing because two other species, the Tibetan sand fox and Rüppell's fox are also sometimes known by this name. The word "corsac" is derived from the Russian name for the animal, "korsák" (корса́к). The corsac fox is threatened by hunting for the fur trade.
The corsac fox is a medium-sized fox, with a head and body length of 45 to 65 cm (18 to 26 in), and a tail 19 to 35 cm (7.5 to 13.8 in) long. Adults weigh from 1.6 to 3.2 kilograms (3.5 to 7.1 lb). It has grey to yellowish fur over much of the body, with paler underparts and pale markings on the mouth, chin, and throat. During the winter, the coat becomes much thicker and silkier in texture, and is straw-grey in colour, with a darker line running down the back.
For a fox, it has small teeth and a wide skull. One source claims that this species can climb trees and has been domesticated in the past.  It is reported to have keen eyesight and hearing and an acute sense of smell. It has a number of scent glands, some of which produce pungent odours, although not as extreme as those found in some other Vulpes species. The glands are found in the anal region, above the base of the tail, and on the paws and cheeks.
Corsac foxes are reported to bark during hunting or when threatening rivals, and to use higher pitch yelps or chirps as alarm calls or social greetings.
Distribution and habitat
Corsac foxes live in the steppes and semidesert of central and northeast Asia. They are found throughout Kazakhstan, Uzbekistan, and Turkmenistan, and through all except the northernmost regions of Mongolia. In the south, their range extends into the more northern parts of Iran, Tajikistan, Kyrgyzstan, Afghanistan, and China, and they can also be found in neighbouring regions of Russia.
Three subspecies are currently recognised:
- Vulpes corsac corsac - northern Kazakhstan, southern Siberia
- V. c. kalmykorum - northern Uzbekistan, Caucasus
- V. c. turkmenicus - southern Uzbekistan, Turkmenistan, China, Mongolia, and neighbouring regions
These foxes inhabit open grassy steppes and semideserts, and avoid dense vegetation and mountainous regions. True deserts with drifting sands are also avoided, as are snowfields more than about 15 cm (6 in) deep. Corsac foxes generally stay far away from human disturbances.
Ecology and behavior
As an adaption to the arid climate in which they live, corsac foxes need little water to survive, obtaining most of the moisture they need from their food. Their diets consist mainly of insects and small rodents, such as voles, gerbils, jerboas, hamsters, and ground squirrels. They may also eat larger prey from time to time, including hares and pikas, and will scavenge for carrion and human refuse. Although predominantly carnivorous, they do occasionally eat fruit and other vegetation, especially when animal prey are scarce. Natural predators of corsac foxes include wolves, eagles, buzzards, and eagle-owls.
Corsac foxes are nocturnal and nomadic hunters of the steppes. They do not have a defended territory, and unlike some foxes, will sometimes form packs. Because they cannot hunt in deep snow, they will either shelter in their dens during harsh weather, or, in the northern parts of their range, they may migrate up to 600 km (370 mi) south in the winter. They have been reported to follow herds of local antelope, relying on them to compress the snow as they pass.
Their prey is often buried in caches.
Corsac foxes shelter in burrows from harsh weather and larger predators. Although they can dig their own dens, these are generally shallow, and they often take over the burrows of other animals, such as marmots, ground squirrels, or badgers. Dens may have several entrances, but are usually less than 1 metre (3 ft 3 in) deep. The burrow is shared between the social packs, with several dens and connecting holes.
Corsac foxes are excellent climbers, but are rather slow runners and could be caught easily by a dog. While they are reported to be nocturnal in the wild, in captivity they are very active during the day. This can be explained by increasing human disturbances, causing them to become active at night to avoid humans.
The mating season starts in January and ends in March. Males will initially fight for access to females, but eventually establish a monogamous bond, and assist in the raising of their young. The mother initially creates a birthing den, which is sometimes shared with other pregnant females, but moves her young to new burrows several times after they are born.
Typically, two to six young are born after a gestation period of 52 to 60 days, although cases of ten pups being born in a single litter have been reported. Newborn kits weigh around 60 g (2.1 oz), and have fluffy, light brown fur that turns yellowish as they age. They are born blind, and open their eyes at around two weeks of age; they begin to eat meat at four weeks, and emerge from the den shortly after. Corsac foxes reach sexual maturity within 9 to 10 months and reproduce in the second year of life. They live up to 9 years in the wild.
The corsac fox is one species within a holarctic clade of foxes that also includes the red fox, the swift fox and the Arctic fox, all of which it resembles. However, the closest related species to the corsac fox is probably the Tibetan sand fox. The immediate ancestor of the corsac fox is believed to be the extinct species Vulpes praecorsac, which lived in central Europe during the early Pleistocene. Fossils of corsac foxes date back to the mid-Pleistocene, and show the species once reached as far west as Switzerland, and as far south as Crimea.
The major threat posed to the corsac fox is poaching. They are slow runners and are easily caught by hunters, and their population has been reduced in areas where they have been heavily hunted for their fur. In the late 19th century, up to 10,000 foxes were killed annually for pelt trade. The general population remains healthy, however, as the corsac fox has proven to be able to withstand great hunting pressures, and their habitats remain intact due to the low population density in its range. Their other main threat is natural disasters, which can cause the numbers of foxes to drop 90% in some areas, but the population often recovers quickly. As of 2008, the corsac fox is listed as least concern in the IUCN Red List.
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