a gestation period of 52 to 60 days, although cases of ten kits being born in a single litter have been reported. Newborn kits weigh around , 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. Evolution 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. Very recent subfossil remains dating to 3000 to 1000 B.C.E. have in found in the Crimea and 0 to 1500 B.C.E. in the Donev River Basin in the northern Black Sea region. Threats The major threat posed to the corsac fox is poaching, as it is a valuable fur-bearing species and has been harvested by humans since the Bronze Age for subsistence and commercial purposes. It is a slow runner and therefore easily caught by hunters; the population has been reduced in areas where it has been heavily hunted for its fur. Traditionally, the corsac fox is often hunted with trained domestic dogs, saker falcons, and golden eagles, as well as caught with traps set at burrow entrances, leghold traps, and firearms. 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 human population density in its range. Other threats include overgrazing by livestock and landscape development; the decline of marmots may also impact the species in some areas, as it often uses marmot burrows as daytime resting locations. The other main threat is