The Tarangire National Park forms part of a bigger wildlife ecosystem covering over 20,000 sq km, which include the Lake Manyara National Park in the north, as well as five other surrounding wildlife controlled areas. The key to this wildlife ecosystem is the Tarangire River, and the local animal migration in the area begins from this river, at the start of the short rainy season around October every year. At the height of the long rainy season, the animals, which include wildebeest, Thompson gazelles, zebra and even African elephants, will be widely spread out over this 20,000 sq km area. When the wet season ends, the animals begin their migration back towards the river and spend the dry season July to October, concentrated in large numbers around the river.

The Tarangire River provides the only permanent water in the area and forms a "dry season retreat" for the animals of the southern Masailand in Tanzania and the Tarangire National Park is reputed to contain some of the largest elephant herds in Tanzania or even in Africa.