increased substantially there from 150 in 1982 to 7,000 in 1992. The blue wildebeest has also been rated as of least concern. The population trend is stable, and their numbers are estimated to be around 1,500,000 – mainly due to the increase of the populations in Serengeti National Park (Tanzania) to 1,300,000 as of 1998. However, the numbers of one of the subspecies, the eastern white-bearded wildebeest (C. t. albojubatus) have seen a steep decline. Population density ranges from 0.15/km2. in Hwange and Etosha National Parks to 35/km2 in Ngorongoro Conservation Area and Serengeti National Park. Overland migration as a biological process requires large, connected landscapes, which are increasingly difficult to maintain, particularly over the long term, when human demands on the landscape compete. The most acute threat comes from migration barriers, such as fences and roads. In one of the more striking examples of the consequences of fence-building on terrestrial migrations, Botswanan authorities placed thousands of kilometres of fences across the Kalahari that prevented wildebeests from reaching watering holes and grazing grounds, resulting in the deaths of tens of thousands of individuals, reducing the wildebeest population to less than 10% of its previous size. Illegal hunting is a major conservation concern in many areas, along with natural threats posed by main predators (which include lions, leopards, African hunting dogs, cheetahs and hyenas). Where the black and blue wildebeest share a common range, the two can hybridise, and this is regarded as a potential threat to the black wildebeest. Uses and interaction with humans Wildebeest provide several useful animal products. The hide makes good-quality leather and the flesh is coarse, dry and rather hard. Wildebeest are killed for food, especially to make biltong in Southern Africa. This dried game meat is a delicacy and an important food item in Africa. The meat of females is more tender than that of males, and is the most tender during the autumn season. Wildebeest are a regular target for illegal meat hunters because their numbers make them easy to find. Cooks preparing the wildebeest carcass usually cut it into 11 pieces. The estimated price for wildebeest meat was about US$0.47 per around 2008. The silky, flowing tail of the black wildebeest is used to make fly-whisks or chowries. Wildebeest benefit the ecosystem by increasing soil fertility with their excreta. They are economically important for human beings, as they are a major tourist attraction.