SWARA

What do the migratory wildebeest­s have to do with ecological balance of the Mara-Serengeti ecosystem? Curtis Abraham explains.

- Curtis Abraham

The African continent has a spectacula­r variety of antelope species – 75 in all -- more than any other continent. The wildebeest or gnu is the most abundant, with an estimated 1.5 million in the Serengeti ecosystem. There are two separate types in the genus of Connochaet­es, the Black wildebeest or Whitetaile­d gnu ( ), and the Blue wildebeest or brindled gnu ( ) and five distinct subspecies. Fossil records suggest the two main species diverged about one million years ago, resulting in a northern and a southern species. But it is only the White-bearded wildebeest that still thrives in immense migratory herds.

When these migratory herds first emerged remains unknown, but the continuous movement of these animals has transforme­d Tanzania’s Serengeti plains over hundreds or thousands of years. The grasses there, which are not nutritious, are cropped by their teeth.

(Antelopes have a special four-chambered stomach, and like their domesticat­ed relatives, sheep, goats, and cattle, all chew the cud. They grab grass with their lower teeth and upper gums, swallow it, and move on. Hours later, they burp it back up and chew in a distinctiv­e side-to-side motion. The antelopes’ four-part stomach evolved to glean nutrients from a diet few other animals can stomach).

Yet wildebeest­s help maintain the Serengeti ecosystem. “They churn the soil with their hooves and nourish it with their urine and dung. Males bashing bushes with their horns in territoria­l displays help keep the savanna from growing into the forest,” according to Richard Estes, an authority on gnus and their migration in the Serengeti. “Even a component in the wildebeest­s' saliva has been found to stimulate grass to grow.

And because the animals move on after grazing, (unlike cattle) the grasses grow back, stronger than ever,” he adds.

During the mating season, female wildebeest­s are seeking food, water and shade. The males, on the other hand, seek to mate. To that end, the bulls hold small territorie­s that they defend until females stream out of the area.

Estes emphasizes that over the years, the movement of wildebeest­s creates conditions for other wild fauna species to thrive. Over 28 depend on the migration. Zebras, for example, chomp taller grasses and reveal the understory for the wildebeest­s; the wildebeest­s return the favour later. They crop the medium-length grasses to uncover even shorter plants, the food of the Thomson's and Grant's gazelles.

Not only do other herbivores benefit. So do 10 large predators including, lions, leopards, hyenas, crocodiles and scavengers such as jackals and vultures.

Wildebeest benefit giraffe, scientists recently learned. A study in Tarangire National Park in Tanzania found that when wildebeest come sweeping through Tarangire, they share the savanna with giraffes, many of whom are taking care of their young. Giraffe calves can’t stand until 30 minutes after birth, and even when they do, their stride is shorter than the adults and they tire quickly, easy prey for predators. More than half of all giraffe calves are killed by predators before they are a month old.

The presence of wildebeest in Tarangire offset the predator pressure on baby giraffes and put it on the wildebeest.

“If the wildebeest population­s continue to decline, then giraffe population­s will also be negatively impacted,” wrote Derek Lee, lead author of the study, working with Wild Nature Institute.

Over the past generation, Africa’s giraffe population has declined by an estimated 40 per cent because of poaching and human encroachme­nt in their habitats. Today, fewer than

ESTES EMPHASIZES THAT OVER THE YEARS, THE MOVEMENT OF WILDEBEEST­S CREATES CONDITIONS FOR OTHER WILD FAUNA SPECIES TO THRIVE.

100,000 survive on the African continent.

Ungulates or large mammals with hoofs have had a tormented history of being the victims of poaching activities. The bison or American buffalo was hunted to the brink of extinction.

Even in Tanzania’s wildlife reserves and national parks where species are protected by law, poachers are having a field day killing wildebeest­s as well as other antelope to satisfy the bushmeat trade for an increasing human population.

It is estimated that 100,000 wildebeest­s are poached annually. While this is only one-third of the American bison slaughtere­d annually during the mid-19th century, Africa’s urban areas, where the bushmeat demand has increased exponentia­lly, are growing at around five per cent annually.

According to the Frankfurt Zoological Society website, poaching remains a major challenge in Tanzania. Snaring often targets abundant species such as wildebeest­s, but are also deadly traps for many other animals, such as predators, elephants and giraffe.

In the Serengeti, tour operators are now supporting the Frankfurt Zoological Society’s De-Snaring Program. The project employs teams of ex-poachers that move through the park, removing snares and freeing trapped animals. Since the project began in 2017, the team has removed almost 30,000 snares and freed 286 live animals. In 2018, they collected over 17,000 snares.

Avoiding predators, including poachers, wildebeest­s choose different routes on their migration each year. Grant’s gazelles, zebras and wildebeest­s behave the same way when they encounter areas of high poaching. But with increasing human numbers, how much longer can the wildebeest avoid a deadly fate?

The wildebeest population in the SerengetiM­aasai Mara ecosystem is the last major population standing. All other population­s have crashed. Only this population and another in Zambia continue their migrations. Previously gnu migrated out of Nairobi National Park to the Athi Plains, but human encroachme­nt and fences south of the park now impede this.

Wildebeest­s are presently not among the estimated one million species that face extinction, many within decades, according to a report by the Intergover­nmental Science-Policy Platform on Biodiversi­ty and Ecosystem Services (IPBES). But they could be in the not too distant future if current levels of poaching continue and if Africa’s human population doubles in the next two decades.

Presently, climate change has altered rainfall patterns over the Serengeti. Wildebeest­s and other wildlife are hemmed in by fences. More roads are being cut into their traditiona­l habitat. Domestic animals bring contagious diseases and farmers are grabbing chunks of their habitat. As if that wasn’t enough, invasive plants are taking hold where native grasses once flourished. Eco-tourism, which has brought many positive benefits, has over-achieved by the sheer numbers of tourist vehicles, which compact soil and carve ruts into grasses on which the gnu thrives. Travellers can help by visiting Tanzania during February, the so-called calving season, when the Serengeti sees many new gnu calves born.

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 ??  ?? ABOVE: The Black wildebeest is characteri­sed by its white, long, horselike tail. It also has a dark brown to black coat and long, dark-coloured hair between its forelegs and under its belly.
ABOVE: The Black wildebeest is characteri­sed by its white, long, horselike tail. It also has a dark brown to black coat and long, dark-coloured hair between its forelegs and under its belly.
 ??  ?? BELOW RIGHT: Blue wildebeest are characteri­sed by a long black mane and a beard of hair hanging from the throat and neck. Both sexes grow short curved horns.
BELOW RIGHT: Blue wildebeest are characteri­sed by a long black mane and a beard of hair hanging from the throat and neck. Both sexes grow short curved horns.
 ??  ?? BELOW: The wildebeest migration takes place over a wide area across Kenya’s Maasai Mara and Tanzania’s Serengeti National Park. These parks are one continuous ecosystem divided by an invisible man-made border. What the animals are in essence doing during the migration is following the rains in search of lush new grass. Taking advantage of the strongly seasonal conditions, the wildebeest are spending the wet season on the plains in the south-east, and the dry season in the woodlands of the north-west. The animals themselves, however, play a role in shaping their environmen­t to their needs just by the sheer weight of their numbers.
BELOW: The wildebeest migration takes place over a wide area across Kenya’s Maasai Mara and Tanzania’s Serengeti National Park. These parks are one continuous ecosystem divided by an invisible man-made border. What the animals are in essence doing during the migration is following the rains in search of lush new grass. Taking advantage of the strongly seasonal conditions, the wildebeest are spending the wet season on the plains in the south-east, and the dry season in the woodlands of the north-west. The animals themselves, however, play a role in shaping their environmen­t to their needs just by the sheer weight of their numbers.

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