Savannas and animal life
Savannas, often referred to as tropical grasslands, are expansive ecosystems characterized by a mix of grasses, occasional trees, and diverse plant life. These regions typically experience long dry periods interspersed with one or two rainy seasons, which stimulate significant animal migrations. Large herbivores, such as elephants, giraffes, and zebras, thrive in these environments, navigating complex feeding habits that enable various species to coexist. The African savanna, in particular, boasts the largest diversity of herbivores globally, with animals like the hippopotamus and various gazelles adapting to different ecological niches.
Predators such as lions, cheetahs, and hyenas play a vital role in this ecosystem, relying on the intricate food chain where plant energy supports herbivores, which in turn sustain carnivores and scavengers. The savanna's biodiversity isn't limited to Africa; it also encompasses regions in South America and Australia, home to unique species like kangaroos and various flightless birds. However, these vital ecosystems face threats from human activity and climate change, highlighting the importance of sustainable practices to preserve their intricate balance and biodiversity.
Subject Terms
Savannas and animal life
Savannas, or tropical grasslands, are vast open spaces that grow a large variety of plant life. Savannas usually endure long periods of drought that are punctuated by one or two rainy seasons. When the rains come, large herds of animals, mostly ungulates, make their annual journey along centuries-old migration routes from the river valleys where they have spent the dry season to the fresh grass on the savanna. Although the principal vegetation is grass, trees or tall bushes appear occasionally on the landscape or along streams.
The huge African savanna is ancient, having probably evolved about sixty-five million years ago. Other areas are newer, some having been created by humans when forests were cleared to accommodate farming. Savannas also exist in South America, largely in Venezuela, and northern Australia.
Plant-Eating Animals
The African savanna varies from very dry regions to areas of swamp, lake, and woodland and can support the largest variety of herbivores in the world. Many animals are capable of living together because most of them have their own specific feeding habits. The hippopotamus, reedbuck, and waterbuck remain near the water, while various gazelles prefer dry areas, receiving moisture from plants. While the zebra chooses open grassland, the wildebeest (gnu), giraffe, and antelope are equipped to forage in the bush and also the woodland by virtue of their long snouts for gathering leaves and stems. All parts of trees and shrubs provide food; while some animals feed on the tough outer parts of grass, others eat the tender, fresh foliage or leaves of wildflowers.
The herbivores found on the African savanna are also the world’s largest land animals. African elephants live in grassland, bush, and forest, in mountainous country, and near lakes. Every day, elephants eat vast quantities of grass, leaves, twigs, and bark, sometimes destroying trees and helping to create savannas. Elephant herds incorporate smaller groups of four to twenty elephants, led by the older females.
The white rhinoceros, weighing more than three tons, is one of Africa’s rarest animals. The herds are composed of small family groups of one male, one or two females, and several young. Its smaller relative, the black rhinoceros, exists more abundantly. Grazing on leaves and branches, the black rhinos are protected by their size and horns and tusks. Humans are their only real enemies. Many of the grass eaters on the African savanna are antelope, which belong to a suborder of animals called ruminants. Equipped with complex stomachs, ruminants eat food that passes from the mouth through the several chambers of the stomach and back again to the mouth. The slow process of rumination, or chewing the cud, provides the animal with more safety from predators as chewing can be accomplished later in a less dangerous place than grazing.
In the savanna of northern Australia are found marsupials—kangaroos, koalas, and wombats. Marsupials also live on the South American savanna, along with the armadillo. Other particular species found in these geographically isolated areas are long-legged, flightless birds—the ostrich, rhea, and the emu.
Predators and Scavengers
When the sun’s energy is converted by plants into food for herbivores, or primary consumers, then the predators and scavengers, or animals who live by preying upon other animals, become secondary consumers in the food chain. Big cats, such as the lion, cheetah, and leopard, are powerful animals who stalk and run down their prey. Lions function in teams, with females assuming most of the work.
African wild dogs are smaller animals with strong jaws, sharp teeth, and a keen sense of smell. They live and hunt in packs made up of six to twenty members. Other predators, such as the hyena and the jackal, kill their prey and feed at night off the carcass of the animal; powerful, far-sighted vultures and marabou stork feed by day, each eating a different part of the carcass. Smaller scavengers—crows, ravens, rats, and insects—move in, helping to dispose of dead bodies that might carry disease organisms. Smaller predators of the African savanna include the desert lynx, which pursues the smaller antelope, and the black spotted serval, which hunts ground squirrels, large rats, and guinea fowl. Other predators are the genet and the fox. Puff adders and cobras poison their victims and are themselves attacked by the mongoose and the secretary bird. The aardvark hunts ants and termites at night. In the Australian savanna, the echidna helps control the insect population with its diet of ants, termites, and other invertebrates.
Various species of monkeys, baboons, and vervets have adapted to living on the savanna by living mostly on the ground, trying to avoid predators. In the Australian savanna, kangaroos are preyed upon by dingoes or wild dogs.
The African savanna has been reduced throughout the twenty-first century due to human encroachment and global climate change. The ecosystem of the savanna is complex and interconnected, and the disappearance of one plant or animal can drastically change its competition and continuation. Sustainability measures are key to the survival of the savanna.
Principal Terms
Carnivores: flesh-eating animals
Herbivores: plant-eating animals
Marsupials: animals having a pouch on the abdomen for carrying their young
Ruminants: grass-eating animals that chew again food that has been swallowed
Ungulates: hoofed animals
Bibliography
Alden, Peter, et al. National Audubon Society Field Guide to African Wildife. Chanticleer Press, 1995.
Combes, Simon. Great Cats: Stories and Art From a World Traveler. Greenwich Workshop Press, 1998.
Irob, Katja, et al. “Navigating Uncertainty: Managing Herbivore Communities Enhances Savanna Ecosystem Resilience under Climate Change.” Journal of Applied Ecology, vol. 61, no. 3, Mar. 2024, pp. 551–63. EBSCOhost, doi.org/10.1111/1365-2664.14573. Accessed 12 Oct. 2024.
Kelly, Morgan. “The Biodiversity of Africa's Savanna Threatened with Large Herbivores Gone.” Princeton Environmental Research, 29 Sept. 2021, environmenthalfcentury.princeton.edu/research/2021/biodiversity-africa%E2%80%99s-savanna-threatened-large-herbivores-gone. Accessed 12 Oct. 2024.
Miius, S. “When Elephants Can’t Take It Anymore.” Science News, vol. 155, 29 May 1999, pp. 341-42.
Sherr, Lynn. Tall Blondes: A Book About Giraffes. Kansas City, Mo.: Andrews McMeel, 1997.
Silver, Donald M. African Savanna. McGraw-Hill, 1997.