Savanna

The wild animals most commonly associated with savannas are herbivores, browsers of grass, palatable shrubs, and tree leaves, and the carnivores that prey on them. The greatest species richness occurs on the African savannas, where climatic changes over geological time have favored the evolution and branching of many different animal species. Indeed, it is probable that the first bipedal humans walked upright on African savannas. The best-known species of African herbivores include the elephant, rhinoceros, zebra, 78 species of antelopes and buffalo, hippopotamus, pig, oryx, gemsbock, impala, waterbuck, kudu, eland, and hartebeest. On the Serengeti plains in Tanzania and elsewhere in Africa the proximity of different types of savanna vegetation, affording browse at different times of the year, has led to the great annual migrations of wild game.

In savanna ecosystems the herbivores are the primary consumers; they browse available producers such as grass. The African savannas also support large populations of secondary consumers—those that eat other animals. Among them are the lion, hyena, wild dog, anteater, and bat. Reptiles, birds, and insects are also well represented on African savannas.

The savannas on other continents show highly impoverished or restricted faunas, in comparison to those of the African savannas. Some highly restricted species are the capybara, a large rodent that lives on the Brazilian campos, and the kangaroos and wallabies of Australia. The prehistoric American savannas once included mammals such as camelids, mastodons, giant ground sloths, and deer. Climatic changes in the Pleistocene that reduced available browse are believed to have contributed to the demise of these species.

Today, domestic herds, especially sheep, cattle, and goats, graze the savannas side by side with the wild herbivores. If not too numerous, they are absorbed by the savanna ecosystem, with no change to the ecosystem. In India and West Africa, however, large domestic herds that exceed the carrying capacity of the land have devastated the savannas. Areas around waterholes and population centers are especially vulnerable to overgrazing. Because most of the world's savannas occur in developing countries, where the local economy relies on exploitation of natural resources, the careful husbandry of the savannas and the methods by which savanna grasslands are converted to farming or grazing use are likely to prove critical to the future survival of these large units of vegetation.