Chad is home to six terrestrial ecoregions: East Sudanian savanna, Sahelian Acacia savanna, Lake Chad flooded savanna, East Saharan montane xeric woodlands, South Saharan steppe and woodlands, and Tibesti-Jebel Uweinat montane xeric woodlands. The region's tall grasses and extensive marshes make it favourable for birds, reptiles, and large mammals. Chad's major rivers—the Chari, Logone and their tributaries—flow through the southern savannas from the southeast into Lake Chad.