Tanzania’s Serengeti ecosystem is like a time machine. As one of the world’s last remaining fully intact grazing ecosystems it provides a glimpse of what others in Australia, Eurasia and the Americas might have looked like when communities of large grazing mammals roamed freely across these continents.
During the Late Pleistocene, which spanned from 129,000 to 11,700 years ago and is sometimes referred to as the “ice age”, populations of these grazing animals collapsed all over the world.
But those populations left a mark: the effect they had on plant communities. Animals and plants shape each other’s evolution. These effects are visible and continuing in the Serengeti. One way this plays out is during one of Earth’s last great herbivore migrations – of zebras, wildebeest and Thomson’s gazelles in Serengeti National Park in northern Tanzania.
Since the early 1970s there have been various theories about what explains the order and timing of the three main Serengeti migratory herbivores. Is it always zebras first, followed by wildebeest and then gazelles? Is that because of competition for the best food? The foraging benefits that smaller herbivores gain from following larger herbivores? Or the risk of being eaten by predators?
