Savanna
Tall, perennial grasses dominate this biome, which occurs in warm, relatively dry regions of eastern Africa, South America, and Australia. Rain is seasonal and ranges from 75 to 150 cm per year. Scattered trees and shrubs usually drop their leaves in the dry season to conserve moisture. As in temperate grasslands, fire plays a key role in maintaining this biome. Large mammalian grazers are abundant and diverse; these include the migrating antelopes, zebras, and giraffes well known from Africa, but also kangaroos and other marsupials in Australia and large rodents in South America. Predator diversity can also be high, as exemplified by lions and other cat species, hyenas, and wild dogs. Dingos are important predators in Australian savannas, but were introduced only a few thousand years ago from southeastern Asia. Before that, the top carnivores included large, now-