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Migration and Competition

Migration is a seasonal movement from one area to another and then back again to take advantage of seasonal abundance of food in different regions. Most animals of the tropical rain forest do not migrate. The climate in the rain forest is the same all year, so there is little seasonal change in abundance of food. On the other hand, the savanna does have distinct seasons and undergoes changes in quality and quantity of vegetation. The great herds of herbivores that live on the vast Serengeti undertake a seasonal migration. In areas that have periodic wet and dry seasons, this prevents overgrazing and allows the animals to find water and feed on the best vegetation.

 The different animals of the Serengeti migrate in a specific order. Because the herbivores of the savanna do not all eat the same plants or even the same part of the plants, they can share or divide the food resources so they are not competing for the same food. No two species can occupy exactly the same habitat and have the same needs. 

The first animals to migrate into an area are the zebras, which eat the top stems of the grasses. Next come the wildebeests, which feed on the leaves and portion of the plant at the base of the leaves. Thomson's gazelles follow. They are small with slender heads and eat low-growing plants and the base of grass stems and leaves. Thomson's gazelle do not feed in areas of tall ungrazed grass, perhaps because their small size makes it difficult for them to see predators.

The browsers divide up the available food of a tree in much the same manner. The long neck of a giraffe allows it to collect leaves and twigs high in the tops of trees. The flexible trunk of an elephant permits it to feed on leaves and shoots beyond the reach of all but the giraffe. Elephants will even uproot trees to gather a few leaves out of their reach. The eland is a tall antelope, almost six feet high at its shoulder. Its large size enables it to browse in the middle portions of bushes and trees.

 The gerenuk, a medium-sized antelope, has a long neck that increases its browsing range, and it often stands on its hind legs to reach higher leaves. Smaller antelope, such as the dik-dik, eat leaves on the lower branches and shorter bushes. Each species eats a different portion of the plant. This divides up the available food, so that the animals are not competing for the exact same food, allowing them to live together and share the resources.

 

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