At the head of the line, a bull was attacking the tree. When the animal moved on, the next wildebeest in line took his place. It seemed the creatures actually were taking turns beating up the tree. They pummel and fray these trees so much, in fact, that Estes concludes wildebeest bush bashing played a major part in transforming the woodlands of the Serengeti in the 1970s and 1980s to savanna like the rest of the park.
Acacias are members of a pod-bearing family of plants that thrive in dry regions around the world.
During different seasons, acacias provide leaves, shoots, flowers and pods as food for hungry animals. They usually flower around the rainy season, and their pods mature in the dry season. Small, nonflying mammals, such as rodents, can be pollinators for some vegetation, but the notion that a large herbivore like a giraffe could serve that function is almost unheard of. But that turns out to be just one part of the relationship between the big browsers and the trees. Biologist Johan T. du Toit, director of the Mammal Research Institute at the University of Pretoria, for example, has been gathering evidence about the role of giraffes in pollination.