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From the air, golden brown specks cover the grass like ants. Zoom in and you’ll see horns, backs and legs moving – all in the same direction. Hundreds of thousands of antelopes cross the savannahs of South Sudan.
The central African country has been ravaged by war in recent decades, making it unsafe for scientific research, and data on wildlife movements there is limited. But a report published today estimates that South Sudan is home to the largest known land mammal migration on Earth.
It is believed that five million white-eared kobs, 300,000 tiang, 350,000 Mongalla gazelles and 160,000 Bohor reedbucks (all species of antelopes) migrate across the landscape every year, moving from the savannas in the south of the country to the wetlands in the north and East .
The estimates come from a 2023 aerial survey of the land around Boma and Badingilo national parks and the Jonglei region, dubbed “the Great Nile migration landscape.” An aircraft flew at a constant altitude above the ground over transects of land, sampling almost 4,000 square kilometers (1,500 sq mi) of an area of 122,000 square kilometers (47,000 sq mi), while an observer recorded what they saw, and a camera, attached on the plane, took a photo every two seconds. The method is often used to assess the distribution of wildlife in large open spaces and was previously carried out in the region in the 2000s and 1980s, during relatively quiet intervals between periods of unrest.
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The latest results have scientists stunned: Although wildlife numbers have declined in many parts of the world due to human development and climate change, these data show that migration has not only survived years of war, but has expanded .
“If the numbers are correct for these species, it appears they have increased since 2007. It appears they have increased even since the 1980s,” said Mike Fay, lead researcher and conservation director of African Parks in South Sudan. He warns that the margins of error are large, but even the lowest estimate of four million antelope is dwarfed by the roughly two million wildebeest moving through Tanzania’s Serengeti, in what has long been considered the largest land mammal migration in the world.
The distances traveled also rival the longest annual land migration in the world. Although routes vary by species, the study found that some tiang traveled more than 3,000 kilometers (1,864 miles), putting them on par with caribou in the Canadian Arctic.
Fay, who has worked on conservation projects in Africa for more than forty years, admits that he has come into contact with natural phenomena on a large scale. He has seen countless elephants, lions, gorillas and other iconic animals. “It’s hard to impress me, right?” he says.
Yet even he was stunned to see thousands upon thousands of antelope running across the landscape.
“How is it even possible that there are so many wild animals?” he marvels. “To me it’s not so much a sentimental thing, it’s more about the biological and ecological capacity of this country to produce so much wildlife. It is truly phenomenal.”
War and peace
The persistence—and growth—of migration is likely tied to decades of instability in the country, Fay says. South Sudan gained independence from Sudan in 2011 after decades of civil war. Soon after, the country descended into its own civil war, which ended in 2018, though local violence continues. As a result, its human footprint has remained low; the United Nations lists it as one of the world’s least developed countries.
“Maybe that provided this opportunity where the animals were left alone for ten to twelve years, and then they became much more numerous,” Fay speculates.
This idea is supported by data from GPS devices attached to about 125 antelopes that tracked their movements over the past year. Although the sample is too small to make any major assumptions, one thing is clear, Fay says: “These animals try to avoid humans as much as possible.” Their tracks form a donut-like pattern, he says, with the antelopes circling around human settlements.
In contrast, non-migratory animals that couldn’t avoid human populations haven’t fared as well. The study cites a catastrophic decline in sedentary species such as giraffes, buffalos, zebras, hartebeests and waterbucks.
“There was a massive proliferation of weapons in the country, and thousands and thousands of people living in the bush. They were not cultivating, so they ate a lot of wild animals and fed the troops with wild animals,” says Fay. While mobile wildlife populations could move into remote hinterlands, sedentary species were easy targets. “Those species got hammered,” he adds.
However, the lack of development has meant that the natural ecosystem surrounding the migration remains more or less intact. South Sudan often calls itself “the land of great abundance” and in many ways it lives up to this, says Fay.
Despite being landlocked, South Sudan has vast freshwater resources, including Africa’s largest wetland, the Sudd, which is fed by the flooding of the White Nile. The name is derived from the Arabic word for barrier, and for centuries the area was considered impenetrable; the Sudd marked the southern limit of the Roman Empire’s expansion into Africa. This remote location has helped protect the region’s biodiversity.
“In most places on Earth, levees have been constructed, or have been overused and degraded, along the floodplains of major rivers,” says Fay. “Whereas here the water comes out of the mountains, hits the gigantic floodplains and just fans out… The fact that these enormous floodplains still function in this modern world is phenomenal.”
It is this unique floodplain that brought conservation biologist Steve Boyes to South Sudan to support African parks in research. As part of his Great Spine of Africa expedition, in collaboration with the Rolex Perpetual Planet Initiative, he wanted to document how the watersheds and rivers – what he calls “the lifelines of these landscapes” – played a role in the annual migration.
He explains that the region has experienced record-breaking flooding in recent years, partly due to pollution from the South Sudanese capital Juba, with plastic and human waste entering the river that flows into the Sudd and blocking the waterways. This could threaten the wider ecosystem and wildlife populations.
“We have water swallowing up the landscape, limiting migration opportunities,” he says. “We have more and more human settlements, which creates a smaller corridor. These dynamics – human development, degradation and the flooding of the White Nile – will increasingly become a problem for migration.”
“Often peace in this post-war wilderness becomes a serious threat to wildlife populations,” he adds.
Possibility
Fay fears the same. Nature has thrived in the “no man’s land” imposed by the conflict, but now that the country is in a period of relative peace, efforts to restore it are in full swing. “Roads are being built, industrial activity is starting up, people are moving more, tribal boundaries are blurring,” he says.
“As they erode and transportation infrastructure becomes possible, we will see a massive collapse of these animals.” He explains that migratory species are particularly vulnerable to linear developments such as roads, because a physical barrier can cut off their migration path and expose them to hunting at the same time.
But development does not have to be bad for nature, he argues. If careful attention is paid, the migration could bring a number of benefits – it could even be “an engine for development”, says Fay, pointing to Tanzania, where the Serengeti National Park, home to a huge wildebeest migration, attracts as many as 200,000 people. tourists per year.
Boyes notes that there may also be opportunities to generate carbon income from the Sudd wetlands or to establish community-run nature reserves that benefit both nature and people.
But Fay warns that conservation is always difficult and takes time. “If you’re going to build an economy around this migration, the lag between the costs and the benefits is large,” he says. Mass tourism is still a long way off in a country that has a reputation for being one of the most dangerous in the world, and as it struggles with a fragile and stagnant economy and the ongoing conflict and crisis in neighboring Sudan, wildlife may pay the price. price.
“Liquidation of natural resources is the fastest way to make money,” he says. “When a country like South Sudan gives up an aspect of development for something that may not deliver tomorrow, that’s where the political will comes into play, and the will of the people.”
At the moment the political will seems to be there. African Parks conducted the research with support from the South Sudanese government and the results will be used to determine the country’s conservation strategy for the area.
At a press conference announcing the results of the study, the country’s President Salva Kiir Mayardit said: “As South Sudan continues to develop, we are committed to transforming the wildlife sector into a sustainable tourism industry. To activate this, I call on the security forces, especially the Ministry of Wildlife and Wildlife and its partners, to prioritize the training and equipping of wildlife rangers to combat poaching and trafficking of illegal wildlife products in protected areas.”
Fay believes funding will be crucial. “The nation has to decide: do we want to sustain this migration or not?” he says. If so, the country needs to invest heavily in conservation and land management to preserve these unique natural areas.
“We have an opportunity,” he says, “but it’s closing right now.”
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