Who Lives on the Savanna? Predators, Grazers, Birds, Waterways, and People

The lion is one of the largest members of the cat family, and males can weigh as much as 250 kg. The video positions it at the top of the savanna food chain. It is also the only cat that lives in groups. At the core of a group, called a "pride," are females related by blood. The females do most of the hunting, sometimes dividing up roles and working together, and they raise their cubs communally. The males mainly defend the pride against intruders.

The video presents research findings on the mane. The darkness of a male's mane served as a "billboard" advertising his nutritional condition and high testosterone. Dark-maned males were not only preferred by females but also commanded respect from other males, had longer breeding tenures, and their cubs had higher survival rates. On the other hand, dark-maned males tended to run hotter at the body surface, were more prone to sperm abnormalities in the hot season, and ate less. As a result, lions in hotter regions tend to have shorter, paler manes.

The cheetah's body is specialized for speed. Most weigh around 30–60 kg, with a slender build, long legs, and a spine as flexible as a spring. It is famous as the fastest land animal, said to reach 100 km/h.

However, the video says the image of a cheetah catching prey at top speed does not necessarily match reality. In experiments using collars fitted with GPS and accelerometers, a top speed of 93 km/h was indeed recorded. But the vast majority of actual hunts took place at much more modest speeds. What determined success was the ability to slow down to match the prey's direction, turn sharply, and accelerate again. Trying to change direction at top speed would mean a turning radius of more than 50 m. But a cheetah can decelerate from 60 km/h to 14 km/h in one second, and at that speed its turning radius shrinks to 1.2 m.

Another characteristic is its extremely low genetic diversity. This is thought to stem from two periods when the ancestral population crashed dramatically: once more than 100,000 years ago and again about 10,000 years ago. As a result, cheetahs are vulnerable to environmental change and disease. Even in healthy individuals, the rate of abnormally shaped sperm exceeds 80%, among other conservation vulnerabilities.

The spotted hyena has a distinctive build, with well-developed forelegs, high shoulders, and a back that slopes downward toward the rear. It has powerful jaw muscles and sturdy back teeth that can even crush bone. Despite its appearance, it is not a member of the dog family. It belongs to its own family, Hyaenidae, and is actually closer to cats.

Hyenas tend to be portrayed as villains, but according to the video they are in fact skilled hunters that catch much of their prey themselves. In one study, increasing the number of hunting participants from one to two raised the success rate by 20%. It is also not uncommon for lions to steal spotted hyenas' kills.

Their social structure is complex, said to resemble a troop of monkeys more than a group of carnivores. Females are thoroughly dominant over males, and cubs inherit their mother's rank from the moment they are born. If the mother is high-ranking, her cub can dominate even older adults. The clan repeatedly splits up and reunites, but cubs born into low-ranking lineages stay low for life, while high-ranking lineages pass their status down from generation to generation. The video describes it as a deeply entrenched hierarchical society.

The African wild dog is a slender, long-legged member of the dog family, weighing around 20–35 kg. Its large, round ears release body heat and also act as antennas that pick up distant sounds. Unusually for a canid, it has only four toes on its front feet. The carnassial teeth of its lower jaw have a specialized shape for slicing meat. Its mottled black, white, and brown coat pattern is unique to each individual, allowing animals to be identified like fingerprints. It once lived across much of the African continent, but its range is now small and fragmented, and it is listed as an endangered species.

What the video especially highlights is the discovery that the dogs decide whether to go on a hunt by sneezing. Before a hunt, wild dogs sometimes make a sharp, sneeze-like exhalation, and when the number of these in the pack exceeds a certain threshold, the pack sets off. This "vote," however, is not equal. When a high-ranking individual started it, fewer sneezes were needed to get the pack moving, but when a low-ranking individual started it, more sneezes were required. Even so, if enough sneezes accumulated, the pack's consensus could override the wishes of higher-ranking members.

Jackals are small canids weighing around 6–19 kg, with slender bodies, large ears, bushy tails, and teeth suited to an omnivorous diet. Among the several species, the black-backed jackal is monogamous, which is rare among mammals, and pairs stay together for life. In a study that followed one pair, their offspring sometimes cared for younger siblings born later, which raised the pups' survival rate.

The African elephant, the largest land animal, can reach 7 t in males. The video introduces it as a keystone species with an exceptionally large influence on the entire savanna ecosystem. In the dry season, elephants dig into dried-up riverbeds with their tusks, creating water holes where many creatures gather. Their habit of knocking down young trees to eat the shoots is also one of the factors that keeps the savanna in a grassland state.

Herds are led by the oldest, most experienced female. Elephants also communicate with infrasound that humans cannot hear. A low growl called a "rumble" carries over long distances, and individuals as far as 2.5 km away may respond. Rumbles may convey individual identity, reproductive status, and possibly even emotional state.

What's more, African elephants can reportedly discern subtle differences in human language and vocal characteristics, identifying the most dangerous people by ethnicity, sex, and age. In response to the voices of adult Maasai men, who carry spears, they bunch together and retreat. By contrast, they reacted only weakly to the voices of men from the Kamba people, who are farmers, and to the voices of Maasai women and boys.

The giraffe, the tallest living land animal, can easily exceed 5 m in large individuals, with the neck alone sometimes measuring 2–3 m. It has the same number of neck vertebrae as humans, seven, but each is extremely long, averaging 30 cm.

The video describes the giraffe's body as "a fierce battle against gravity." Its head sits more than 2 m above its heart. To push blood that high, its blood pressure averages over 200 mmHg, and in large individuals or with the neck stretched straight up it can approach 250 mmHg. When drinking, the head drops below the heart and then quickly returns to a high position. The difference in height is far beyond anything that causes dizziness in a person standing up too fast. Giraffes have bypass vessels connecting the carotid and vertebral arteries, and valves that prevent backflow in the neck veins. They also have genes for tolerating high blood pressure and building sturdy bones. Meanwhile, the heart itself, which does the pumping, is of an ordinary size for an animal of its bulk.

Giraffes are also known for having the shortest sleep time in the animal kingdom. Wild adults have been observed to get by on an average of 30 minutes of sleep per day.

Zebras are members of the horse family, growing to more than 2 m in body length and over 200 kg. They have short manes, sturdy teeth for grinding tough grass, and the black-and-white stripes they are known for.

The reason for the stripes was long a mystery. Theories included camouflage in the grasslands and body temperature regulation, but the video says the leading theory today is that they repel insects. In a study published in 2022 comparing zebras with plain-coated impalas, flies circled both at about the same rate, but successful landings on zebras were less than a quarter of those on impalas. The study also found that stripe width made no particular difference. Many mysteries therefore remain, such as why stripe width varies between species and why the stripes are narrower only around the face.

The wildebeest, a bovid weighing close to 300 kg, has a boxy head, two large curved horns, a gray body, a black mane, and a beard. Wildebeest are constantly on the move in search of food and water, sometimes traveling 800–1,600 km in a year.

Emblematic of this movement is synchronized birthing. Births are concentrated in the first few weeks of the rainy season, and at times as many as 80% of all calves are born within just three weeks. By giving birth to more young at once than predators can eat, the herd is thought to dilute the chance that any one calf will be attacked.

The great migration is also a matter of life and death. On the Mara River, which flows through Kenya, mass drownings during crossings occur almost every year. One study found that mass drownings of more than 100 animals occurred in 13 out of 15 years. The video, however, says these deaths cannot simply be called wasted. In the years studied, an average of 6,250 animals, or 1,100 t of biomass, entered the Mara River. That works out to the equivalent of ten blue whales' worth of carcasses flowing into a medium-sized river every year. Because it takes about seven years for even the bones to decompose, wildebeest carcasses are an important source of nutrients for the river ecosystem.

The African buffalo, a size larger than the wildebeest, can exceed 3 m in length and reach 900 kg in large individuals. In males, the horns fuse at the base to form a hard shield that protects the skull.

Though known as a ferocious and dangerous animal, the buffalo is also highly social, and herds can reach 2,000 animals. To keep the herd from scattering, buffalo display behavior resembling democracy. When moving, each individual faces the direction it wants to go, and the direction with the most "votes" is adopted. A lead female then guides the herd that way.

Their defense is also skillful: when danger approaches, they surround the calves in the center of the herd and respond to the distress calls of captured herd members by coming to the rescue. There is even an observed case of a herd retrieving a calf from both lions and a crocodile. The video says that against the defense of their massive bodies and shield-like horns, even the king of beasts cannot easily make a move.

The hippopotamus has a barrel-shaped body and can weigh as much as 5 t. It has an enormous mouth and continuously growing incisors and canines. Its eyes, ears, and nostrils are lined up on top of its head so it can watch its surroundings while its body stays submerged. Its blood-like red sweat is actually an acidic pigment secreted from beneath the skin. This pigment has been found to work as a sunscreen that absorbs ultraviolet light, and also as an antibacterial agent that inhibits bacterial growth.

Hippos also support the ecosystems of lakes downstream. They graze on the savanna at night and excrete in the river during the day. In the process, they were carrying large amounts of silicon from land into the river. According to one study, hippos transport 400 kg of silicon per day, influencing 76% of the total silicon flowing into the lake. Silicon is the material for diatom cell walls, and diatoms are the foundation of the lake's food web. The video therefore explains that hippos hold a key to the lake ecosystem.

Rhinos have thick, overlapping, armor-like skin and impressive horns. The horns are not bone but are made of keratin, the same material as human hair and nails. Their eyesight is weak, but their senses of smell and hearing are excellent. Several species live on the savanna, and the large white rhino can reach up to 3.5 t. Even with that bulk, it has been unable to escape human hands and has been hunted relentlessly for its horn. Especially tragic is the northern white rhino subspecies: only two females survive, and the video says its extinction can be considered certain. Still, some people are trying to save the subspecies through methods such as in vitro fertilization using preserved sperm. The video says the history of the southern white rhino subspecies, which recovered after falling below 100 animals, offers a glimmer of hope.

The impala is a medium-sized bovid weighing around 40–80 kg, and only males have lyre-shaped horns. At the base of the black tufts on the hind legs is a scent gland called the metatarsal gland. The video focuses on its teeth: the lower incisors and canines are lined up like a comb and can move about 2 mm. Impalas take turns grooming each other's heads and necks with these comb-like teeth. Grooming is usually repeated 6–12 times, strictly alternating. There is no inequality in which higher-status individuals receive more, and even unrelated males reciprocate as equals. The purpose is thought to be removing ticks from places an animal cannot reach with its own mouth. This is a rare cooperative relationship among wild animals other than primates. Because even calves one to two weeks old do it, it appears to be an instinctive behavior acquired through evolution.

Thomson's gazelle is a small bovid weighing around 15–35 kg, with a pale coat, a black side stripe, a white belly, and two horns that curve slightly backward. It can reach a top speed of 70 km/h, but when chased by predators it sometimes makes a strange movement. Called "stotting," it involves leaping high in place with all four legs held stiff. At first glance, this looks like nothing more than wasting energy while fleeing. In reality, however, wild dogs tended to target gazelles that stotted fewer times. Gazelles also stot little in response to stalking predators like cheetahs. From this, it is inferred that stotting serves to show off the gazelle's fitness to predators, and that predators take it into account.

The warthog is a member of the wild pig family weighing around 50–150 kg, with a large, flat head, upward-curving tusks, sparse bristles, a mane along the back, and warts on the face. The warts are thought to be cushions that protect the face during fights between males. Because its face is large and its legs long but its neck short, it feeds in a posture with the front knees resting on the ground. In the rainy season it eats short grass, and in the dry season it digs into the ground with its snout and tusks to eat roots and other food. It sometimes uses burrows dug and abandoned by aardvarks as dens. It enters them backward so that its tusks face out of the hole, ready to confront any predator that comes along.

Baboons are monkeys weighing around 10–30 kg, with dog-like muzzles, powerful jaws, and sharp canines. Their tails are less dexterous than those of forest monkeys, but they can climb trees. As primates living on the savanna, they have long been studied as a mirror of human society.

In a study that followed olive baboon troops for many years, low-ranking males in stable troops showed high cortisol levels and blood pressure, and weakened immunity. In other words, the lower the rank, the greater the stress. On the other hand, another study found that the top-ranking individual in a troop was under far greater stress than the second-ranking one. The video poses the question of whether this might have something in common with human society.

Another example concerns a troop that humans had observed for many years. In 1983, tuberculosis broke out from contaminated meat at a garbage dump, and half of the males that had been feeding there died. Those that died were the males aggressive enough to monopolize the dump's resources, and those that remained were a non-aggressive group. This tendency persisted ten years later, and even low-ranking males were not under as much stress as low-ranking males in a typical troop. Because males leave their birth troop at adolescence, none of the males that survived that time should still have been there. This means that newly arrived males had learned and carried on the troop's own culture.

The ostrich is the largest and heaviest living bird, reaching up to 2.6 m tall and 135 kg. Its wings are used for balance when running, for courtship, and for other purposes. Its eyes, 5 cm in diameter, are the largest of any land animal and bigger than its brain. It can reach a top speed of 70 km/h, can run for long periods at 50 km/h, and covers 3–5 m in a single stride. Within a group, the struggle for survival begins even before birth. In East Africa, two to seven females each lay eggs in the same hollow, and 30–40 eggs gather in the nest. But one bird can incubate only about 20 eggs. The lead female pushes all the eggs beyond what she can cover out of the hollow, and the pushed-out eggs die. The leader apparently avoids pushing out the eggs she laid herself.

The secretarybird stands about 1.2–1.5 m tall and has a unique appearance combining an eagle-like body with the longest legs of any bird of prey. On its head is a crest of feathers resembling quill pens, and it has short, sturdy toes for stamping on prey. Its hunting method is kicking. In a study in which a trained bird kicked a rubber snake and the force was measured with a hidden sensor, a single strike reached about five times the bird's body weight, and its foot was in contact for only about 0.015 seconds. It is thought to have honed this split-second strike for hunting venomous snakes.

Vultures are large raptors that glide on broad wings, and many species live on the savanna. Their heads and necks are often sparsely feathered or bare, and they have hooked beaks, keen eyesight, and powerful stomach acid. By arriving at carcasses within hours of death and clearing away about 70% of them, they are thought to prevent the spread of disease. Their featherless heads don't easily get caked with filth even when thrust inside a carcass, and they also help with temperature regulation. Vultures are also highly capable fliers: a case in which one collided with an aircraft at an altitude of 11,300 m over Côte d'Ivoire has been recognized by Guinness World Records as the highest-flying bird.

The great white pelican is a large waterbird with a wingspan of up to 3.4 m, an expandable throat pouch, short webbed legs, a pinkish face, and white plumage. Unusually among birds, it fishes cooperatively, with many pelicans forming a circle to trap schools of fish and sometimes herding them into shallow water. When it comes time to eat, however, the cooperation quickly collapses, and it is not uncommon for pelicans to fight each other over fish.

Here the video turns its attention to the savanna environment itself. The savanna is a grassland environment, found mainly in the tropics, that is neither forest nor desert. Depending on the definition, it is widespread in central to southern Africa and is said to cover about 20% of Earth's land surface.

Why doesn't it become forest? The video says rainfall alone cannot explain it. According to one study, with annual precipitation of 650 mm or more, trees should flourish on grasslands and eventually turn them into forest. That grassland persists anyway is thought to be due to dry-season fires and to herbivores such as wildebeest eating tree shoots. Put another way, without these influences, the wetter parts of the savanna are an unstable environment that would turn into forest.

Trace the water that nourishes the savanna, and you arrive at Lake Victoria, Africa's largest lake. It is the largest tropical lake in the world and the second-largest freshwater lake by area. Yet its history as a lake is short: it is thought to have dried up completely about 15,000 years ago. Today's lake is a relatively young one that formed when it filled with water again. Tropical fish called cichlids flourished in the lake and diversified into many species. In the 20th century, however, they began going extinct one after another at human hands. By one account, as of 1992, about 200 of more than 300 endemic species were already extinct or endangered. The main cause is said to be the Nile perch, a predatory fish introduced for fishing.

Water flowing out of Lake Victoria becomes the Nile. The Nile has two sources: the long White Nile, which begins at Lake Victoria, and the Blue Nile, which begins at Lake Tana in Ethiopia. The shorter Blue Nile carries more water and more fertile soil. The video says the black mud carried by the annual floods nurtured a civilization in the desert.

That picture changed dramatically in the 20th century. Completed in 1970, the Aswan High Dam controlled the annual floods and brought a stable supply of water and electricity. But the price was that it blocked the fertile soil. After its completion, more than 98% of the sediment carried by the river came to remain in the reservoir. Cut off from its supply of soil, the Nile Delta is gradually sinking and has begun to shrink as it is eroded by Mediterranean waves.

The Nile crocodile is a large reptile that can reach 6 m in length, with a back covered in bony plates and a powerful tail. Its bite force is among the strongest in the animal kingdom. Most of its prey is fish, but it sometimes eats wildebeest, zebras, and even hippos. By one account, up to 200 people a year are killed by Nile crocodiles. It is thought that these are mainly people doing laundry at the riverside who are attacked by mistake. On the other hand, crocodiles are unusually attentive parents for reptiles. The mother guards the nest and removes the soil on top so the hatchlings can get out. Mothers have also been observed gently carrying hatchlings in their mouths to the water.

The Nile monitor, up to 2 m long, is Africa's largest lizard. It swims skillfully, using its flattened tail like a rudder, and can stay underwater for more than ten minutes. Besides fish and birds, it also goes after eggs and carrion. According to the video, this diet helps keep the Nile ecosystem in balance and prevents the spread of invasive species and disease. Its numbers can therefore serve as an indicator of the whole ecosystem, and a sharp decline points to possible environmental destruction nearby. It is also known for laying its eggs in termite mounds. The temperature and humidity inside the mound are ideal for incubation, and the eggs spend about six to nine months there.

Finally, noting that wild animals are not the only ones living on the savanna, the video introduces the Maasai. The Maasai are a semi-nomadic people who live across Kenya and Tanzania and move with their cattle. Following the seasonal rains from pasture to pasture and giving the grass time to recover, they have long coexisted with wildlife. However, the video points out that their history has not been smooth, including evictions tied to the establishment of national parks, and that land disputes continue to this day.

The video closes by saying that this land moves as one great web in which people, grass, rivers, and countless wild animals influence and support one another.