A game reserve (also known as a wildlife preserve or a game park) is a large area of land where wild animals live safely or are hunted in a controlled way for sport. If hunting is prohibited, a game reserve may be considered a nature reserve; however, the focus of a game reserve is specifically the animals (fauna), whereas a nature reserve is also, if not equally, concerned with all aspects of native biota of the area (plants, animals, fungi, etc.). Many game reserves are located in Africa. Most are open to the public, and tourists commonly take sightseeing safaris. Historically, among the best-known hunting targets were the so-called Big Five game in Africa: rhinoceros, elephant, Cape buffalo, leopard, and lion, named so because of the difficulty and danger in hunting them. In a game reserve, ecosystems are protected and conservation is usually key. Indigenous wildlife in its natural habitat help in providing an environment where growth in numbers at a natural rate can occur. Some game reserves contain several ecosystems, ranging from valley bushveld, savannah grassland and fynbos to riverine forest and acacia woodland; this provides a dramatic improvement on the types of wildlife that are present and the numerous species of birds that thrive in these environments. Wildlife conservation is a costly endeavor for most African countries. One of the more common forms of generating income to establish a sustainable economy to provide for wildlife conservation is known as wildlife viewing tourism. However, this attraction still does not generate enough to establish wildlife conservation. For regions that suffer political and economic instability, sustainable trophy hunting may be the only feasible source of sufficient income. Once established, another aspect to consider is the management of the land being used for hunting. Naturally, wildlife decreases with the increase of human presence which puts a strain on the quality of hunting.